I picked the most likely candidate in the overgrown cassava bed down the hill and dug it:
That’s barely worth feeding to the chickens!
Back when I grew cassava in North Florida, the roots would grow huge in the loamy sand. Here, I don’t know. People do get decent harvests, but my guess is the shade and the clay hurt our yields.
I’m going to try again and see if I can do better. These were grown in loosened soil but I think they could have used more sun.