When it comes to the library, get a selection of books from varying levels. Books published before 1970 are going to have fewer 'mature themes.' See if she is interested in 'Little House on the Prairie' or 'Ozma of Oz'
We loved 'The Phantom Tollbooth' and anything by EB White.
also the Dinotopia illustrated books.

Take a look here for more ideas:
http://www.hoagiesgifted.org/hot_topics.htm

Once you've found a few books at 5th grade level that she likes, ask the librarian for more suggestions.

Coaching available, at SchoolSuccessSolutions.com