.... First thing tomorrow I'm calling the town to make sure it's OK first.....
The friends I alluded to, who do their annual east coast park turf safaris, do not go waltzing into city halls asking "is it ok?". Because then you run the risk of getting an arbitrary "no". Simply a "safe answer" because some pencil jockey thinks you'll harm the earthworms, or leave holes, etc... So if you're skittish (that there may be a no md'ing rule), you do it this way. Either:
a) look it up for yourself. If that town's municipal codes, rules, ordinances park rules, etc... are on-line, you merely look to see if there's anything that says "no metal detecting". If you see no such rule, then presto, it's not prohibited.
b) if the town doesn't have their park's rules and muni codes on their website, and you're still skittish, and still feel the need to talk to a live person, then you can do this: Ask them: "where can I find a listing of all the park rules and/or municipal laws, charter, etc... here? Eg.: no fireworks, dogs on leash, closes at sunset, and so forth. ".
They will point you to a link perhaps. Or point you to where it exists in binder form for you leaf through. If they try to change the subject and say : "what is it that you needed to know?", you stick to your guns and say: "To know where the public can avail themselves of the laws pertaining to the city and park usage, in printed form"
Because all laws are public info. They HAVE to be available to the public to read SOMEWHERE. You don't want to fall victim to the "no one cared TILL you asked" psychology.