It's a clip on earring. In your second pic, you have it laid out correctly. Between the clamshell looking piece, and the hoop piece, there would have been a hinge between the two wire ends. It would just snap closed on your ear lobe.
Ooh thats definitely it, wasnt thinking of clip on ones thanks! the wire part broke when cleaning, but looks like there is a hinge on the back part.
Ty everyone! yeah probably missed some stuff myself, wasnt there long because I was at a different spot before and its hot here, but i'll definitely be back to do the backyard... does give me some hope about other places people have already detected like the sidewalk spots in town.