went back again for another 10 min successful digging in the same site again, brought up a mysterious looking star button, weird back to it, pretty sure its pewter, but here it is.
If that silver sliver is a coin, it's probably Mexican. And if the straight edges are 20 mm, it's a one 'bit' coin; 1/8th of an 8 reales coin.
If the length is 16 mm, it's an eighth of a 4R coin; or 1/2 of one 'bit' (real).
Don.......
Great digs! You had a very productive 10 minute hunt. If I had a site that produced 18th century finds like that you couldn't drag me away from it. Get back out there and see what else you can find. Without giving to much information can you give us some details about the type of site and history of it?