What made Tom visit the Ewell's house in the first place in chapter 19?

Tom says he passed by the Ewell house every day on his way to work at Mr. Link Deas's farm, where Tom picks cotton and does other farm work. Tom confirms that one day last spring, Mayella asked him to chop up an old chiffarobe with a hatchet, but that was long before the November day in question. After Tom performed that favor for her, Mayella often asked him to help her with odd jobs around the house as he passed by. She offered him a nickel the first time, but he refused payment, knowing that the family had no money. He said he helped her out because she didn't seem to have anyone else to help her, and that he never went onto the Ewell property without being invited.