Welcome to TNet. You might want to post in "what is it"... as the really good ID guys lurk there and try to put up the fastest ID. There are several killers guys... Charlie P from NY comes to mind. He IDs some really tough stuff.
My take: That reeded edge makes me think coin... however, there are no numbers or letters on the it, all coins (found in the USA) have writing on them, country of origin, date, motto, etc.
That hole is directly through the center, and sort of square. Makes me think escutcheon, or decorative plate. It only has designs on one side, so that was the only side meant to be seen.
Good luck on the ID!