Boy, this issue goes to show the power of the lobbyists and experts that surround the beltway. Over the years, the food pyramid has changed dramatically, and remains a political football to kick back and forth. The first pyramid was adopted in 1992, changed in 2005 and now reports are that the new version will be a plate showing how much of each food group an adult person should eat for healthy weight.
Here are some examples of past pyramids:

Nutrition experts from the Harvard School of Public Health created the Healthy Eating Pyramid, and updated it in 2008.

USDA’s post 2005 food pyramid

This is the pre-2005 pyramid for USDA.