aka sunchoke,topinambour; Helianthus tuberosus; Asteraceae (aster family)

The Jerusalem artichoke is from the New World (not Jerusalem), and is only distantly related to the globe artichoke (Cynara cardunculus) that you buy in the grocery store, though they are both in the aster family.  Globe artichokes are a type of thistle, actually, while this plant is a type of sunflower with an edible root.  It grows up to 10 feet, with characteristically rough, hairy stems and leaves:

Jerusalem artichoke is native to most of the US except the desert southwest, and is considered a weed by some authorities.  In this area you can find it on the forest edge along the riverbanks.