Got this at a local auction a few weeks ago.  I figure it's US Army, but I can't figure out how old it is or where it might've been placed.  It looks like a hat badge to me.  The pin is obviously a home-made replacement, but the badge appears to be authentic.  I don't see any markings on it.  Nothing else at the auction gave any indication of how old it might be, except that there were a lot of very old things there. This was in a trinket box.  I suspect it's early 20th Century, but I'm wondering if it might be earlier.  Civil War vintage would be nice.

Any help would be much appreciated.