This is prop for cosplayers of Prince Wu from the Avatar: Legend of Korra series. It's the little medallion on his scarf in the shape of the Earth Kingdom symbol.
Use some yellow paint to get it a more accurate color to the show. I used a metal washer and a flat neodymium magnet to attach to my costume.
Add a magnet or some other type of fastening solution to attach it to your scarf/costume.