Did you know that only 16% of Americans know that popcorn is a whole grain?
MyPyramid.gov suggests that atleast half of our grain intake should be whole grains.

Grains are divided into 2 subgroups, whole grains and refined grains. Whole grains contain the entire grain kernel — the bran, germ, and endosperm.

Examples include:
whole-wheat flour
bulgur (cracked wheat)
whole cornmeal
brown rice

Refined grains have been milled, a process that removes the bran and germ. This is done to give grains a finer texture and improve their shelf life, but it also removes dietary fiber, iron, and many B vitamins.

Some examples of refined grain products are:
white flour
degermed cornmeal
white bread
white rice