You can use them on the sword in the stone in the fantasyland courtard. You use each pin for one try at pulling the sword out of the stone, and if you are successful, you earn a rare pin.
You can go to Fantasyland Courtyard, and ride either PPR or ALR! Unfortunately, you don't always get a SITS magic when you ride though You put the magic on your lanyard, step near the sword in the stone, and then use the magic