Do you remember your very first book? I do! It was "Baby Animals". I looked the book up on a search engine a few years ago and the illustrator was Garth Williams. I knew his drawings also from "Charlotte's Web" and the Laura Ingalls Wilder books. Imagine my surprise when I found out that although he was born in America, his parents were both English and he and his family moved to England when he was ten years old. (I find his life story interesting, you may read more about him here.)
Recently, I spent a good amount of time trying to help my Dad in choosing a present for a shower gift, he had been asked to buy a book for a baby shower, and then, to write a personal note in the book for the child. After our discussion, he settled on "The Uncle Remus Stories". That is the main book that he remembers from his childhood, although, he didn't have the book, he only knew the stories that were told to him.
So, what was your very first book? I hope you remember it with great fondness.