Compositae, also known as the Aster family is a very large family of the plant kingdom. Named for the characteristic of composite flower structure, they include Sunflowers, Jerusalem Artichoke, Globe Artichoke. and the Chicories (endive, dandelions, and the like). Other obscure vegetables in this family include Salsify, Scorzonera, Cardoon, and edible Chrysanthemum.
Sweet Potatoes are part of the Morning Glory family (Conculvacea), and are one of the few members of this family that humans use for food.
Grasses show up in our diet mostly as grains, and corn is just that. Sweet corn, is picked when the grains (kernels) are very young and still sugary and moist.