Now I know it says The Book of the Day in the title but this is one of my all time favorites. The Giving Tree by Shel Silverstein. It's a bout a boy and a tree and how much the tree loved the boy. I remember very clearly when I first had someone read this book to me. It was in kindergarten and the teacher was reading it to us. It hit me very hard. I recommend this to anyone whether you're into books, children's books or not. It's a very touching story and you're bound to remember it for a very long time.