Just finished Grisham's "A Painted House", which is supposed to be semi-autobiographical. The 7-year old boy who narrates the story is the child of cotton farmers in Arkansas, with the story taking place during harvest in 1952. It's good, evoking the time and place, but not a thriller in his usual mode.
Turns out that Grisham is actually 50, so he's 10 years younger than the hero. That may explain the math errors in the book, which only a crazed bureaucrat would pick up on. Supposedly the family (3 generations) is farming 80 rented acres. The situation is that the crop is good, but pickers are needed to harvest the cotton. The pickers are a family of "hill people" and a set of 10 Mexicans (no blacks in the story, which was a surprise). Grisham gets a variety of characters and plot points out of the intermixture of locals and pickers.
Unfortunately, he says the cotton is 500 pounds per acre (sounds about right), so they have 40,000 pounds of cotton to pick. Given the workforce (10 Mexicans, 6 hill people, father, grandfather) and an average 400 lb per person, the cotton could have been picked in a week or 10 days. The book spreads the picking over a month or so, then a flood ruins a third of the crop, so the family heads to Flint to work in the car factories.