When I was a kid growing up in the 50's and 60's in Alabama. Poor blacks, teenagers, and poor whites, worked picking and gathering crops. Many boys I grew up with at 12-16 years would bail hay, pick peaches, rake up pecans. Many farms had a pick your own deal, where you picked two bushels of peas, beans, etc, and you got one, the farmer got the other for him to sell. Still have a lot of those around. Pecans could be done the same way, you rake and pick them up, you get a bushel, the owner gets a bushe. Not many people want to do this anymore.
My grandmother did it in her 80's to get pecans. She also picked her own blackberrys and wild plums. Made good jelly and cobblers. Made good pecan pies, and pecans for other receipes. She picked wild muskedines for homemade wine and jelly. Don't see much of that any more. A lot of older blacks would pick things for halves.
I never saw any Mexicans picking or gathering anything.
By the way, I live in Alabama and with our illegal law, 3 months after it took effect, our unemployment rate dropped 2 points below the 4 surrounding states. Hmmm, some illegals were taking legals jobs. We dropped to something like 7. something, while the other states were hoovering around 10%. We also have a Republican governor, state senate and house for the first time since reconstruction. They cut spending without raising taxes.