At two I let my offspring play with my cards under supervision, and got her a pack of playing cards for her own. Which got lost.
So when the kitten chewed up one of my Gypsy Witch cards, I gave her the rest of the pack. She likes her cards with the witch on the back, and I occasionally get her to match them up by suit or number for number and pattern recognition (she's 3.5 now). She has her own deck now, a trimmed mini Hanson-Roberts, that she calls her narrow cards. They're hers, but are kept with mine so that she doesn't lose them all.
Child-friendly decks? I've found she has had luck with Lenormands, because they're small and few so she can handle the deck easily. And the simple pictures are good for her too. Other than that, brightly-coloured and sturdily laminated decks work well.
And cheap