Sash buckle? Brooch? How old and what the heck is it?

[FreeBirdTim]

I found this "buckle" about 8 inches down under a tree root. Not sure what it is or how old. I don't see any evidence that there was a pin attached to it and it is very thin. Any help would be appreciated!

 

[ARC]

Almost resembles a picture frame border insert. ? ? ?

 

[FreeBirdTim]

That's an excellent guess, but I don't think that's what it was used for. If you had a photo in it, not much of the photo would be visible. I think a photo frame border would be more oval and less oblong in shape. It's also very small, measuring around 1 5/8" by 2 1/2".

I knew this was going to be a toughie to ID! It's going to annoy the heck out of me until I figure what it is and how old it is.