Scout first tells us about the "Cunningham tribe" in Chapter 1, when she relates that young Boo Radley had "become acquainted" with the Cunninghams, who hailed from Old Sarum, an area of northern Maycomb County. The Cunninghams were a ne'er-do-well group that hung out at the Dew-Drop Inn and drank stumphole whiskey.
Nobody in Maycomb had nerve enough to tell Mr. Radley that his boy was in with the wrong crowd.
In Chapter 2, Scout tries to defend Walter Cunningham Jr., a classmate who has hookworms and no lunch money. Walter is too shy to stand up for himself, so Scout tries to explain about Walter's poor family to her teacher, Miss Caroline. Instead, Miss Caroline spanks Scout for her efforts.
Scout knew about the Cunningham family because Atticus had once represented Walter's father. Mr. Cunningham, a poor but honest farmer, told Atticus that he didn't know when he'd be able to pay for Atticus' services.
"Let that be the least of your worries, Walter," Atticus said.
Atticus explained to Scout that he would eventually be repaid, and sure enough, Atticus was right. Mr. Cunningham paid for Atticus' counsel in trade--hickory nuts, smilax, holly and turnip greens.