Dug this today at abt six or seven inches. Heavy. On the back, at least two, maybe four pins where it was mounted on something. Nice greenish patina. Thanks for looking.
Bridle rosette I think, with the loop on back broken off.
Like the one here: http://www.liveauctioneers.com/item/6476563
I don't know if the stated age is correct or if these are a bit later