My husband bought this book, The Christian Mother Goose, for our kids. Our kids love this big book. Instead of reading it, we are singing the words to the tune of familiar nursery rhymes like Twinkle, Twinkle. I think this is a brilliant idea of teaching kids about Jesus and God's grace. Children can easily understand it because of the simple words. Best of all, the kids can easily remember it because these are familiar songs.
One of my favorites is the Jack and Jill. The lyrics go like this:

Janck and Jill went up the hill to fetch a pail of water.
A man there said, "If you drink this, You'll still be thirsty after."
"But there is water Jesus gives, so won't you ask Him first,
to give you Living Water so that you will never thirst."
Up Jack got and home did trot, a whole mile and a quarter,
To tell the Good News to his friends, about God's Living Water.
The book is written by Marjorie Ainsborough Decker and illustrated by Sarah Gibb.