Since we don't often play card games that involve jokers, we always give the jokers to D1 to play with. She knows very well exactly how many cards are hers, and if you hand her only one, she'll follow it up with, “More card?” (I wonder how many cards she would be able to “count” in that sense. Probably not more than three.)
Last weekend as we were unpacking boxes we came across a box of Veggietales cards I'd had for awhile. We decided the time had come, and gave them to D1. Sure enough, she was quite thrilled to be able to “Play cards!” with her own set.
She's never actually watched Veggietales, but she's chopped up a lot of vegetables with me, so she loves going through them and naming them: “coo-cum-BER, may-TOE, pair-GUS, cart.”
We developed something that vaguely resembles a game, wherein we each get a set of cards and take turns setting them down in matching piles. Most of the time, though, we just go through them and name what we see, or spread them all over the place and then pick them up.