If you're going to "keep checking", just be sure to look things up for yourself. That is: don't go walking in to ask deskbound clerks, cops, etc.... Because no matter how carefully you might try to ask "is metal detecting ok?" or "is there anything that prohibits it?", they might either 1) answer your question as if you were asking their permission (like, an answer that might go like this: "we would prefer that you didn't"). or 2) They'll morph something inane, like "don't disturb the wildflowers" or some such nonsense, and tell you "no". (afterall, why should they care? what do you THINK the easy answer is going to be afterall?)
To check it for yourself, city codes are usually available on-line, at the various city websites. If there's a search function, just do a search on words like "metal detectors", etc.. If the city (or county, or whatever) doesn't have a website with their laws/rules, then they are usually available, for public viewing, down at city or county halls walk-in lobby desk.
Satisfy yourself that it is silent on the issue. Because if you go asking, you may get an arbitrary "no", when no one would probably have ever have really cared, or ever noticed (till you asked that is).
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