The Magic: the Gathering (MTG) set Mirrodin (MRD) was released on Oct 2nd, 2003. It includes 3 token cards.
Mirrodin is an expansion set in the Mirrodin block. An expansion set in Magic: The Gathering is a pool of cards released together and designed for play in the same environment. Standard cards and tokens in a set can be obtained at random through booster packs. Sometimes a set will contain promo tokens that are given away as prizes at Friday Night Magic (FNM) or special pre-release events.