Enemy Pie is a great book for teaching about friendship! It's one of my favorite books to read to kindergartners, this time of year, and we read it today in kindergarten. The story is all about how a father tricks his son into playing with a boy who he thought he didn't like. After spending the day together, he realizes that he doesn't actually have an enemy. He has a new friend!
If you'd like to see an animated version, click on the link below.
http://www.sno-isle.org/kids/ and then go to Tumblebooks. You will need your library card number to login. There are MANY wonderful books on Tumblebooks and this service is free through the public library. It's worth investigating!