When I was young during the summer when we'd drive to Greene for livestock feed, we'd see an old bus parked by the fields bordering the Chenango river, fields in which grew green beans, a bus which provided transport for those Negroes (as we said then) who picked the beans. It was a moment of quickly passing contact with another world, strange to a child of dairy/poultry farmers. I've no idea where the pickers spent the night, presumably a tent or the bus.
These days the people who harvest our fruits and vegetables are almost all immigrants, mostly undocumented. That leads to multiple issues, as described in this good Tamar Haspel piece for the Post. If undocumented immigrants are deported and Trump's wall is built and is effective (big "ifs"), will citizens fill their places? Could higher wages attract enough workers? Or would innovation come to the rescue, providing machinery and robots to do the harvesting, perhaps at the cost of changing the nature of the produce?