what story details reveal that these characters are farm people

The setting the characters, like the Joads, live in is rural. They talk avout farming, the land, animals. Steinbeck describes the arrival of the tractors. They crawl over the ground, cutting the earth like surgeons and violating it like rapists. The tractor driver does his job out of simple necessity: he has to feed his kids, even if doing so comes at the expense of dozens of families.