Helianthus tuberosus, a tuber-forming perennial sunflower native to the US, is a fast-growing biomass producer that is capable of aggressive expansion past its original planting sites. The tubers are comparable to knobby potatoes but contain inulin rather than starch - some folks are sensitive to this though certain cooking methods can reduce the gastric impacts. The flowers provide an important food source for many native insects, while the stems and foliage are beloved by deer. Small burrowing mammals are fond of the tubers, and you may find new patches forming due to their work.
This plant is very good at colonizing disturbed sites and can handle dry soils. The large amount of green material it produces can be an excellent source of green manure in chop and drop systems. We've had success interplanting this with Apios americana, groundnut, and have found that the canopy these plants provide together creates excellent conditions for growing mushrooms below them.