Wow - thats dead exciting.
I was skeptical about it as the large stone in the field doesn't look overly weathered and gave me the impression of being quite new, but i guess you have to see it first hand. The ones that are part of the drystone wall are definately interesting, they look older.
Have you checked it out on an o/s map.
I tried locating the wood yard on google earth, but the one i found didn't really match up. perhaps looking at an aerial shot to identify the location would be a plan?