Nana tree roots

Robin and I usually do a bit of gardening at Nana's on a Sunday. At a certain time of the year her lawn starts growing mini trees and we have a bit of fun pulling up the sucker roots of the Sumac tree we think is responsible. The roots are often thicker than a thumb and about 2" below the surface of the lawn. We got pieces out which were as long as me - as you can see from the picture