The green plastic button of the Trylon and Perisphere is one of a set of 6 buttons shaped like buildings at the fair..
The plastic used was commonly used for sewing buttons at the time, called 'acetate', and there is a shank on the back of each one for sewing onto clothes.
There were charm versions also, but they all have the unmistakable ring near the top so they can dangle from a bracelet or necklace.
Other buttons, of various materials, including bakelite. glass and celluloid can be found depicting just the Trylon and Perisphere.
Pam is a Life member of the National Button Society