Oh I love it!! Another case of asking "can I detect?" and getting great things morphed to fit the person's "pressing question". Welcome to the club Miller-pony: You are the now the latest member of the "No one cared ... TILL you asked" club. In other words, it's just as Jason and Silver-finder99 say: No one cared. And as you can see, silver-finder apparently has no problems. Yup, even "taking" those priceless pennies and dimes he found. Gulp, I bet you some of them may have even been silver or wheat pennies. Oh no! Say it isn't so!!
Jason, the sad thing is the bored desk-bound bureaucrat who answered miller-pony with an answer like that, could probably, given enough legal wranglings and semantics, be a true statement. Afterall: let's say you or miller-pony went and harvest all the roses out of the rose garden in the park, to sell at the local flea market, .... then you KNOW you'd be in violation of the prohibitions of "collecting", or "taking" and so forth. Right? Hence why is a mercury dime or gold ring any different? And even if you could try to say that gold ring didn't belong to the city (and instead belonged to the person who lost it), well then duh, now your simply in violation of your state's lost & found laws. IT NEVER ENDS!! No matter how you slice it, you're going to be in violation of SOMETHING, if you asked long enough, and hard enough, of enough bored desk-bound bureaucrats and lawyers.
Millerpony, in the future, do NOT go asking city clerks "can I?" type questions. Instead, look it up for yourself. If you see nothing there saying "no metal detecting", then presto, it must not be prohibited. And if you want to worry about all this ancillary periphery stuff applying (collecting, taking, alterations, lost & found, property laws, defacement, IRS tax codes, cultural heritage, harming earthworms, etc...), then I have some advice for you: take up another hobby.