In my past, I would say that these three books are the ones that have had the most influence on the person I am today.
The Rainbow Fish was the most popular book around when I was in the first grade. The sparkly scales of the fish caught all our attention-deficit minds, but what was more was that it went beyond just a pointless tale to entertain us as kids, it actually gave valuable moral fiber. It reminds children that while it is important to know that they are special, it also sweetly reminds them to see the goodness in others; it may be harder to find than the blaring, sparkling scales of Rainbow Fish, but appearance will only get you so far.
What I believe to be one of Shel Silverstein's best, The Giving Tree tells the story of a selfless love. Unlike Romeo and Juliet, where they are just some infatuated teenagers with more hormones than the live produce of America, a tree gives all that it can to a present-minded boy that cares deeply about what he thinks he needs. Love like this isn't shown in most children's books these days, as the book kept emphasizing how the tree met the boy's needs, even though it had not much too offer. But what struck me was how the tree was happy when the boy was happy –– it reminds you that love isn't about what you're able to receive, rather it's more of how you become happy when you know that you have something to be able to give to another.
Lastly, I think this book is just a bitter-sweet representation of both the joy and sadness you get in life. You get your victories, you get your losses, and as long as you're alive, there's nothing stopping you from living.