This is a native plant, widespread in the eastern United States. The name comes from little edible tubers that grow on the ends of some roots. It is hard to eradicate as some bit of root is always left in the soil. It is pushy and takes over in our Schoolyard Garden if we don't keep after it.
New plants pop up at the ends of the roots.
If you look at the stem of this plant it is triangular. If I remember correctly that was one of the identification clues I picked up somewhere. Look it up online and you will find more about it as it is a pest. Another, more famous, sedge is papyrus . It was an important plant in ancient times as it could be made into a flat sheet to write on.