Marcy Hooper and the Greatest Treasure in the World, by Stephanie Tolan, 1991

The one thing Marcy Hooper feels she can do well is read -- maybe not so well that she remembers how the words are spelled, but well enough to be carried away to the magical worlds of princesses and dragons in the stories she likes best. But one day when she runs away from home she finds herself in a cave where her storybook tales are real, and her search for treasure brings unexpected results. Geared for elementary school readers.