Looks like stamped steel, and thin. This is just a guess, but maybe a previously painted hair barrette. I see what looks like two attachment points on the back, perhaps where the clip thingy used to be? Cool find, whatever it is.
It looks like one of those things you put on the wall to cover a hole. Larger round ones for old wood burner hook up. I used to see these in granny's house. Gary
I've been staring at it for several minutes, but I got nothing. Very cool find. I'd be excited to find that. Does it appear to have had an attachment on the back, above and below the swan? Can't tell from the pic. If so, maybe a brooch