If it was not transported there, dropped and lost years ago, then it may be from right where you found it, Finding nice Quartz crystals in Regolith is not all that uncommon, especially here in the east coast USA. Regolith is a layer of loose weathered rock intermixed with soil, It's the superficial material covering over the solid rock below.
Depending on your landscaping and desire to find more, I'd suggest opening up a small two foot by two foot test pit as near to where you found it as possible, dig down a few feet to see if anything else is there. If not, either it's simply a lost item transported there some time ago (from who knows where), or what little quartz you do have floating loose in your soil, is simply not worth the effort to find more.
Interesting yes, and very much a fun project too, but probably not a deposit that's worth working in any economic sense. You'd have to find some really exceptionally beautiful crystal to make that much effort and re-scaping worth your while.
My crossed fingers and hopes for success go out to you!
PS: Keep in mind that you're not far from the very popular quartz collecting sites around Herkiner, NY. It''s very likely just a clinker brought home from one of the previous owners field collecting ventures that was just left out in the yard (seems the more likely scenario).
Quartz var Herkimer Diamond HUGE SIngle xtl! Fonda, Mohawk Twp, Montgomery Co., NY 5.75 x 4.5 x 4 inch These often will erode out of a pocket- that is, a cavity or void that formed when the rocks formed that the crystals grew into. I would invest in a pick axe and dig in the soil around the boulders (near the base of them) or near the bases of trees where eroded crystals might have been trapped. Also if you dig and discover an intact pocket, then that is the score. There is no hard and true method for finding pockets or digging- it's a lot of luck. At least, that has been my experience at the crystal digging sites I have been to in California and the northwestern US. One of those quartz veins on your land might have a crystal-bearing pocket in it, if the vein is large enough, but again- it's random and kind of rare. Good luck, and nice find! Matt and Mark,
Thank you so much for all the helpful info and the encouraging words. Mark, I think I will dig down further into the original site- I only dug out about a square foot. Matt, I will try under some of the large tree roots and also around the base of the boulders like you suggested. I'll keep an eye out for veins as well. I just wanted to be sure I was headed in the right direction. Thanks again!!! Hopefully I'll be posting again with my findings!!
P.S. In terms of value, any idea how much the quartz I already found would be worth? I know I'm not digging for diamonds but I was just curious... I was thinking about attending the Gem show in NYC in November. It would be my first time attending a show- would I be able to get appraisals there on anything I find?
Thank you!!!! There is also another mineral show that is closer to you. It is in Albany, NY, and held at the NY State Museum in mid-February. There will probably be several dealers there who could easily tell you what your crystals are worth. As SUSAN R said, show your examples around at the Albany Capitol District show and other shows or any club meetings that you attend. But I must tell you that your pictured examples don't appear to be much. Rather than broken pieces of quartz, your quest should be for intact crystals with intact crystal faces and as little damage as possible. CHEERS......BOB Susan, thanks. I will check the Albany show out as well.
Bob, thank you as well- I assumed as much but thought it was worth a check.
Thanks again!! Melissa - your find, though not worth the big bucks, is the kind of find that got most of us here into this hobby. The recommendation to check the Albany show is good - also look into joining that club, if it is closest to you. Even though you may not be able to attend the meetings, the club likely has field trips which you could attend as a member - which would provide invaluable experience on what to look for, how to look for it, and how to get it out of the ground. A club membership is a great thing for a "newbie". Best of luck with your new endeavor! Melissa - Back a couple responses of yours ago...The NY City Show would certainly have people willing to share an opinion on your find.
As Susan Robinson pointed out - Albany has a show (and a great club)... if you want to wait until February. There are other shows coming up. I'm not sure where/how you define mid-state NY but Bristol, CT has a show 21-22 Oct. The Stamford, CT club has a show 4-5 Nov. The Morris Museum
in Morristown, NJ has a show Thanksgiving weekend. These are all club sponsored shows. There are plenty more clubs and shows around. I can't agree more with the folks suggesting you find a mineral club close by.
I also sent you a PM with additional comments on finding a club and on the 'appraisal' of your find.
Have fun. Mark K. Thanks Mark and to all that have commented with their great advice and encouragement! I definitely will join a club... or two or three :) I'll be digging all weekend now!
Happy rockhounding to all! Hi Melissa,
Not sure where you are in "central New York", but It can be interesting walking over farmer's newly plowed fields (of course with permission) in the Herkimer/Fonda area after a rain storm. Especially in the spring. The plowing and harrowing turns up quartz crystals that have been lifted by frost action and the rain washes them off so they glint in the sun light.
Don Melissa
What you have found is known as a "Herkimer Diamond", it didn't come from your white quartz veins,, tho you may find some openings in the white quartz with regular quartz crystals in them, yours came from a pocket in 'dolostone' , similar to the rock stuck in your crystal, you will need to look for rock similar to the stone in your crystal.
As for value, I would guess it to be between 20-40 dollars at most, mostly because of the size, not the condition,
Still a very good find to get you started !
New York Gem and Mineral Clubs
http://www.rockhounds.com/rockshop/clubs/new_york.shtml
Good luck and injoy your new hobby ! ! !
Keep On Rockin' I will give a bit more of my opinion. While MARK H's nice crystal is a Herkimer Diamond quartz specimen, MELISSA's examples are broken pieces of quartz. They may be from that area of NY and be associated with Herkimers but, cannot by themselves, be considered "Herkimer Diamonds". It may be a matter of semantics, but just like broken pieces of massive calcite are not "calcite crystals", broken pieces of NY State quartz from near Fonda are not "Herkimer Diamonds".
Next point is WAYNE's value. We might quibble, but if MELISSA's pictures are accurate, I don't think there will be much interest. I do not see any evidence of crystal faces in her specimens.
Of bigger importance is that a beginner immediately concerned with "value" of a find is getting off on the wrong foot. Beginners should be most interested in identification of their finds and how to proceed from that to continue their new found hobby; joining a club, attending local shows etc etc. IMHO, collecting specifically for value should only come somewhere down the line. CHEERS......BOB 
While it might not be an outstanding example, it certainly has crystal faces, take a better look at the photos. I know that pictures can be deceiving, but I feel like see a number of features on that example which are consistent with herkimer style quartz. Compare her first image with the back of the crystal I posted earlier. This one also had additional fused/intergrown crystals that are now broken off. A broken chair is still a chair, even if it is better used as firewood now. :)
Melissa,
There has been a lot of talk about Herkimer and the quartz crystals referred to as Herkimer diamonds. It sounds like you don't live very far away. So why not a field trip to Herkimer and see what it is all about on a larger scale? Call it an educational field trip. Try the Herkimer diamond Mine by the KOA campground or the Ace of Diamonds Mine just a short distance up the road. Both are easy to get to and cater to beginners. You can see the rock type these crystals are found in and just how hard it can be. You might not find any large crystals but lots of small ones can easily be found. You can easily find information on line about these digs.
And yes, if you want to be hammering on rock, get yourself a proper hammer. A carpenter's claw hammer is NOT the proper tool. A good geologists hammer or brick mason's hammer is what you need. Estwing brand tools are not cheap but worth the money, particularly if you think you are going to get into this hobby. Melissa,
good advice from Al O. To add to his comment on hammers: carpenter's claw hammers can be dangerous. The steel is not tempered for striking rocks, and sharp chips can break off and fly. My favorite hammer was an Estwing 3 lb. crack hammer. I used it a lot more than my geo pick so my vote would be for a good Estwing 3l lb. crack hammer for a first investment (with a good Estwing chisel) and the geologists pick second.
Don 
Donald is right, the rock crack hammers (also known as drilling hammers) are essential.
I would have not found ANY pockets without that tool!!
Then you will need multiple cold chisels. Get one with a hand guard, it'll save you from a bruised to broken hand... These are a must because you will need to crack the rock and chisels have the ability to not only crack the hard rock, but also split it a little bit so that the crack moves further into the rock. Just hammering away without this will not get you very far...
A rockhound must is a pry bar, or even multiple bars. I have many different ones, from an 8" all the way to this 3 foot, heavy and reinforced bar (I call it the mountain mover, the one images is just $30)... These bars are essential because you will need a way to move large hunks of rock. Using just a hammer will not get you very far. I just got the one below this year and its transformed my crystal hunting abilities for the better!!!
Finally, you'll need a shovel to remove all trailings from the hole... I use a short shovel, not a long regular shovel as its easier to shovel stuff out of holes with a shorter pole...
