Timpsila

Pediomelum esculentum, synonym Psoralea esculenta, common name prairie turnip or timpsula, is an herbaceous perennial plant native to prairies and dry woodlands of central North America, which bears a starchy tuberous root edible as a root vegetable. English names for the plant include tipsin, teepsenee, breadroot, breadroot scurf pea, large Indian breadroot, prairie potato and pomme blanche. The prairie turnip continues to be a staple food of the Plains Indians. A related species, Pediomelum hypogaeum , the little breadroot, is also edible, although the plant and root are smaller. Another species, Pediomelum argophyllum (syn. Psoralea argophylla), was probably harvested for food only in times of famine.[a]

Source: Wikipedia