Golden Filly Series Books 1-5 By Lauraine Snelling 

1. The Race 
2. Eagles Wings 
3. Go for the Glory
4. Kentucky Dreamer
5. Call for Courage

Lot 5, Written in the early 1990's,  Name Written on the Box, Expect to find a name written on each book inside, Stains on the edge of the pages. No unpleasant smell.  I have numerous other young adult books to list in this genre.  I hope you'll check them out.