Popcorn - this actually doesn't have a US Government standard - amazing!!!

Popcorn or Popping Corn is a type of maize which explodes from the kernel and puffs up when heated. Special varieties are grown to give improved popping yield. Some wild types will pop, but the cultivated strain is Zea mays subsp. mays, which is a special kind of flint corn.
There are no U.S. Standards for popcorn and popcorn seed functions as foreign material under the U.S. Standards for Corn.

USDA/GIPSA
http://archive.gipsa.usda.gov/tech-servsup/visualref/grain_gallery/HTML%20Pages/popcorn.html