Looks like part of a door to an old coal stove. Usually these are covered with layers of rust coming out of the ground, but hard to tell from the pic whether it is cast iron or not. If so that would explain the fragment, because old coal stoves are usually found that way...in many many pieces. Might want to check into Pittston Stoves, they used the star motif in their designs and even the Star of David, which is what I think you have there.