I had a buckwheat pillow at one time. It worked great.
Take notice! NEVER wash and then dry a buckwheat pillow. Don't ask me how I know this.
I should confess and explain.
Once, a loooong time ago, I had a buckwheat pillow. Loved it. I like a pillow that stays "cold" and the buckwheat pillow stays cooler than most pillows. Yada, yada, yada....one day I decided the pillow needed to be laundered and refreshed, so I stuck the pillow in my washing machine, on the gentle cycle, and washed it. My guard was down and I didn't think it through when I stuck the damp, heavy, pillow into the clothes dryer. I hit the "on" button and left the pillow in the dryer. As I left the basement, I could hear the heavy pillow clunking around in the dryer. When I later returned I opened the dryer to take out my nice clean pillow. The cursing that followed was a tour de force performance! That pillow had ripped apart at the seams and there was buckwheat all over the dryer, in the filter, and clogging the vent hose. Buckwheat was everywhere. How the gas dryer didn't catch fire was a miracle! It took me days to take the dryer apart and vacuum out all the buckwheat.
What a total butt-hole I was to wash and dry a pillow that was stuffed with buckwheat.