The picture I linked is of a buckwheat pillow. Had no idea they were a thing before today.
What about silk or bamboo pillow cases?
I've only ever really used cotton pillow cases and cotton stuffed pillows. I recently upgraded to a foam pillow that I'm enjoying.
That looks more like dirt than buckwheat.
They are buckwheat hulls. It would be disastrous to stuff your pillow or mattress with something mice find delicious.
Durable asphalt pillow!