What an interesting question! And, a tough one, because there aren't very many mentions, and when they are mentioned, it is very brief. I found a couple. The first is in chapter 2 when Scout is saying that Calpurnia is to blame for her being able to read and write. She would sit Scout down and force her to write something well, and if she did, Scout was awarded with "an open-faced sandwich of bread and butter and sugar." There is also, later, a mention of crackle-bread that Calpurnia makes for Scout, in a moment of kindness. During the trial they go home for supper, and in chapter 21 it mentions Cal serving "potato salad and ham." She was the one that did most of the cooking in the household, so there are a lot of mentions of them eating, or her getting supper or lunch ready, and those dishes mentioned above are a few of the specific ones named. I hope that helps!
ITS CRACKLE ME BREAD