Goes The Weasel

X was first discovered by Native Americans over thousands of years ago. Evidence of X from 3600 BC was found in New Mexico. The English who came to America in the 16th and 17th centuries learned about X from the Native Americans. During the Great Depression, X was comparatively cheap at 5-10 cents a bag and became popular. Thus, while other businesses failed, the X business thrived and became a source of income for some struggling farmers. During World War 2, sugar rations diminished candy production, causing Americans to eat three times more X than they had before. X also became the first food item to be deliberately cooked in a microwave oven. What is X?