I'm not sure if this is the same book to which ThinkTink refers, but there is a book of Hidden Mickeys available ubiquitously in all four parks. It has a yellow cover and the words Hidden Mickeys very clearly printed on it; if Magic Kingdom is your first park, you will be able to find it at either of the small shops on either side of the entrance plaza. It is also available inside that park and the other three. Of course, if someone can give you the title, you can purchase it for your daughter in advance. There are also various different Hidden Mickey websites you could access with her, which you can find on Google. I wish you both a great trip!