What genre of books did Bud's mother like in Bud, Not Buddy?

In Chapter Nine of Bud, Not Buddy, Bud goes to the mission for breakfast, but his "family" (the people who helped him in the food line and provided him with brown sugar for his oatmeal) are not there. He eats alone and then heads to the library, where he sits under a tree and waits for the doors to open.

Once the library opens, Bud enters and sees the same librarian that had been...

In Chapter Nine of Bud, Not Buddy, Bud goes to the mission for breakfast, but his "family" (the people who helped him in the food line and provided him with brown sugar for his oatmeal) are not there. He eats alone and then heads to the library, where he sits under a tree and waits for the doors to open.

Once the library opens, Bud enters and sees the same librarian that had been there before. Bud asks this friendly librarian for a pencil, a piece of paper, and a book that will tell him the distance between two cities. The librarian provides him with these things, and also comments that she recognizes Bud-- she used to see Bud and his mother come to the library "a long time ago." The librarian then recalls:

And if I remember correctly you and your mother had quite different tastes in books. I remember your mother used to like mysteries and fairy tales, isn't that so? ...And you're the little fellow who used to come in all the time and ask Miss Hill for books about the Civil War, aren't you?

All of this is indeed true, and Bud is pleasantly surprised that this woman remembered his and his mother's preferences in literature.