For my play time, I used some giant erasers from Dollar Tree. I really like using these because of the thickness and firmness. The price isn't half bad either. You can easily carve both sides of the eraser and get two fairly large stamps for a buck. I'm not worried about it lasting forever. Chances are by the time it falls apart on me, I'll be ready to carve a new one.
I'm preparation for my play date, I went to Pinterest and got lost looking at all the fun stamps. I settled on a feather, dandelion, seed, and a peeps bunny.
Bonus: During February, I created a Snoopy stamp to use for some Valentine's Day postcards. I thought I'd share it here as well.