Thidwick the Big-Hearted Moose, by Dr. Suess is my absolute favorite children's book. Granted, it is not as well known as some of Dr. Suess's other classics, but it is a wonderful book.
The story is about Thidwick, who is a kind and gentle moose. He allows various animals who are weary and need homes to ride on his antlers. One by one animals pile up onto his antlers, weighing poor Thidwick down and causing him to lose all his friends. He handles his situation with grace, and all ends well. Aside from having a delightful rhyming meter, it has a great moral (something hard to find in many children's books these days).
I give this book to every child that means something to me. Inside, I inscribe a reminder to be kind, but be wise.
I can't say enough good things about this book. I highly recommend it for the little one in your life.