Uhhh, you've found "countless" old coins and romans in the UK @ "random stone walls" ? Or are referring to USA "random stone walls" ?
Because if you are referring to the USA, then .... you'll have 100k USA of us md'rs clamoring to know which "stone walls" you're referring to. Where they can waltz on out and find "Roman coins".
Because: Last I checked: We're lucky to approach the explorer-era, of our east coast history. And while hunting: "any old field" in the UK might be fruitful (since there's so much history there). Yet in the USA, when you hunt "any old field" , you are probably in for a b*tt-load of silence and sterility.
and "big pennies" tom!..they are there! look for breaks in the walls, and very large trees close to the wall.these places are where they stopped to have lunch, and sit in the shade! the old yankees built those walls, and they spent a lot of time on them and they lose things same as anybody else!
(h.h.!)
j.t.