Take a book, bring a book

Oh wow. This is so cool. A family in Oak Park set up their own little library in their front yard. I totally want to visit and contribute a book. If you were contributing a book to a "Take a book, bring a book" library such as this, what book(s) would you contribute?

I enjoy Incredible Change-Bots (by Jeffrey Brown) so much that I might go to my local book store, buy a copy and drop it off at the Weiss Library.