A bowl of oaten cereal.
oaten definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
of or made of oats, oatmeal, or oat straw
oaten definition by American Heritage Dictionary
Of, made of, or containing oats, oatmeal, or oat straw: oaten fodder.