I Spy Little Bunnies by Jean Marzollo, illustrated by Walter Wick.

This is a charming board book version of the popular I Spy series.  The puzzles have been made easier by simplifying the graphical elements.  The rhymes by Marzollo have also been made simpler.  Photographs have been mixed in with the text so they are rebus-like, perfect for emergent readers to begin to understand how reading works.  The puzzle and game aspect of the book may draw in more reluctant beginning readers who will not realize they are learning about reading while they play.