How do you get the Key to Rewards cards?

[Ult_kh_ff_fan]

Ok I've finished KH1 and KH2 completely and know what happened in CoM but never found the time to finish it. Well now I started playing again and the other game I had sucked and I decided to start fresh. My question is in each world I can't find the key that opens the key to rewards room and no FAQ has been helpful. Can anyone help me? I want to know where to find it in Traverse town, Wonderland and the Colliseum.

[gorgonseye72]

all the cards suck

[The Graceful Assassin]

Sorry I can't remember how I got it. I know that once you get it, it's permanent and you can use it in any world. But the reward usually isn't worth it anyways, usually just a stupid card

[master_of_the_key]

You get the key of rewards from fighting enemies....it just randomly appears at the end of a battle instead of getting a card to use on a door