First, Go Dog Go by P.D. Eastman. This is one of my favorite books ever. This book taught me to read. I read it again and again and again when I was learning. I can still recite parts of it by heart.
I remember loving all the funny-looking dogs, and looking through the book to find them again and again, and, of course, the dog with the crazy hat, who asks again and again, "do you like my hat?"