The Jolly Postman
This book brings together two things that delight me to no end: mail and interactive books. Janet & Allan Ahlberg's The Jolly Postman is beloved for good reason. Readers get to follow the jolly postman as he delivers letters to a familiar cast of fairy tale characters -- and then we get to study the envelopes and open the letters inside to discover hilarious surprises about the humdrum, day-to-day lives of these larger-than-life figures. This story is clever and wild and layered and just a heck of a lot of fun. A necessary addition to every little library!
P.S. There's a Christmas edition, too!