Favorite Books

We have a cool thread about books we have banned from our rooms, but I'm curious about the reverse.

What are your "must have" books?

I love Llama Llama, Pout-Pout Fish (I know others hate it), and Pete The Cat.

My favorite off-beat book is a Halloween one. "Goodnight Goon", a new-to-me parody. It's hilarious and I bought a copy for my house, even though my kids are 2nd-8th grade.