I wanna bet it's the necklace, BUT like others have pointed out, it's not exactly a odd item (but would be an "interesting" one I think!)...
If it's a ring, it's not mine or it wasn't but is now lol
As long as it's not a funky body part, I'm good.
Just off the top of my head it could be:
Nail
Coin
Glass (broken? I have heard of weirder things!)
Big Rock (maybe someone really needed grit!)
Ciggerette Butt (my community gardener has a nasty habit of tossing them around)
Zip Tie
Shell
Snail Shell
The Necklace
A glass eyeball
Someones Bridge
A contraception product (
)
A feminine product (HOW they would get these things I have NO CLUE)
A bottle cap
Plastic Army Man
Jewlery of some kind other than the necklace
A gold tooth
Marble
A crochet hook
a mouse or rat
I don't know what else, I'm out of ideas.