Leonard Copsey’s more a seafood market than it is a restaurant; so if you have a nearby kitchen in which to cook hard-shell crabs, flounder, or shrimp, it’s a great place to shop. With the Chesapeake Bay just to the East and the Atlantic Ocean just a short hop over the Eastern Shore, Mechanicsville is in the heart of Mid-Atlantic seafood country, where the exalted culinary rituals include steaming crabs and shrimp with peppery spice mixtures, stuffing flounder with fresh crabmeat, and eating oysters by the dozen.