What are the five special rocks Bud always keeps with him in Bud, Not Buddy?

The reader finds out near the end of Bud, Not Buddy that the rocks Bud keeps in his suitcase (inside a tobacco bag) “with writing and numbers on them” are actually mementos from each band performance of his father.   His mother kept these rocks as special memories because Calloway himself had inscribed them with the date of the performance as well as the city. 

When Bud is riding in the car with Mr. Calloway, Bud finds a large collection of similar rocks in the glove box.  When Bud shows Mr. Calloway a few of his own rocks, Mr. Calloway gets angry and accuses Bud of stealing them.  Bud finally convinces Mr. Calloway and the other band members that the rocks aren’t stolen, but were given to Bud by his mom (Angela Janet).  This is the altercation that makes Mr. Calloway realize that Bud is truly his grandson.  It is at this point that the reader finds Herman E. Calloway crying in his bedroom due to the magnanimity of this information.