One of my favorite books when I was a kid was Katy No Pocket (I think that was the name). It was about a mother kangaroo who didn't have a pocket to carry her baby kangaroo. She wandered into the city, met a carpenter who gave her his carpenter apron, and then she had pockets galore to hold her baby and other little animals.
This kangaroo has a great pocket with lots of fun things to put in her pocket, including a baby kangaroo! I might need to break down and buy this set, Build-a-Roo ($25.96, set of 10), it brings back good memories. :) It's versatile enough to be used for many occasions - birthday, Valentine's Day, new baby, thank you, general love and friendship..... hmmm.... so many stamp sets, so little time. :)