Bottlecaps on the AT Pro ring in the penny/dime range and pulltabs (usually) ring in the nickel range or below. Foil is indiscriminate about where it rings in at.
Incidentally, scotk9 and I hit a baseball field last night for about an hour. I took home over $2 in change and a small .925 silver ring with a yin yang on it that rang just like a dime. No gold, for either of us. Since my regular historic spot is overgrown, I think I'm gonna go on an athletic field rampage this month until they cut the grass again.
Hey Terry, got anything similar for football and baseball fields?