A Mint Set from the US Mint contains uncirculated specimens of current coins. The mint makes oodles of them and sells them to collectors at exorbitant prices. Packaged with some of these sets is a small copper token with P (Philadelphia) or D (Denver) on one site. Enterprising coin dealers break the sets apart and sell the uncirculated coins separately. What is left, then, are oodles of unsold P or D tokens. You can buy them on eBay in lots of 50 for a few US dollars.