Guess How Much I Love You, by Sam McBratney, was the first book I ever read to my daughter, and did so when she was only days old. I actually wept at its sentiment and chalked it up to postpartum hormones. But two years later it can still bring tears to my eyes.
This story is about a little bunny, Little Nutbrown Hare, who is trying to tell his daddy how much he loves him. No matter how far he reaches, or how high he jumps to show him, his daddy always does him one better. Little Nutbrown Hare keeps trying, even up til it's time for him to go to sleep.
The illustrations, by Anita Jeram, are beautiful and have even been made into wallpaper and wall art.
This is one book that my daughter has let me read to her from the beginning, so I can recommend it for very young ages. We have the board book version and it has stood up well to being read dozens of times, and even having a tear or two fall on its pages.