I've been making "Cozies" with field corn (aka seed corn and feed corn) for several years. There is an inner cotton container with the corn inside, and an outer washable pillow case made from cotton flannel. Heated in the microwave, these hold their heat for about 30-45 minutes, and can be reheated repeatedly for years. My Mom took one to bed with her every night in the winter, and began using it during the day too when she was over 95 years old.
The scent when heated is like corn. My husband always asks me to "please pass the butter" when I wrap one around his neck.