Welcome. MD State property is off limits. State Parks are open but restricted. See the MD DNR site for metal detecting restrictions. You can still get permission from private owners. Check out a local club or meet up with a TNetter. I have gotten permission to hunt in places I should not have simply by asking. Get out there and get to be known as "That guy who metal detects!". People will flock to you. Also try a wanted ad on Craigslist. I know a guy who is running an ad and getting results on the shore.
Ed D.