Thought it was a rev. war hat plate..

I received permission for a 200 acre field surrounded by Lake Champlain. My first good find was at 15 inches. As I dug it out, it appeared to be a hat plate. I left as is and carefully cleaned it when I got home. It turned out to be upside down in the first photo. It does have a metal attachment piece on the rear. Also the emblem seems to be attached to the plate. Any thoughts?