Just to be clear, rumors usually involve a falsehood and a sense of malice, whereas gossip involves discussion about an individual with another individual or a group of people. Scout gives Miss Caroline the generally accepted gossip about the Cunningham's poverty, not with malicious intent, but simply with the desire to inform the teacher.
Scout explains to Miss Caroline that Walter, being a Cunningham, cannot accept a loan of a quarter because it is unlikely he will be able to pay it back. The Cunninghams, like many who rely on agriculture for their livelihood, often engage in a barter system when they need something from others, swapping supplies for services and vice versa. The Cunningham family have a reputation for not taking charity and for holding their own in society with their bartering, which reflects a sense of civic duty and a personal pride in their own ability to make their way despite their financial hardship.