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.
I switched to buckwheat pillows a few years ago and I've been a fan. It's a really interesting texture that you can move and shape really easily, but then when you apply pressure to it, it firms up and holds its shape. So, you get a really supportive pillow that's molded to your head and neck (For reference, I'm a side sleeper). The only downside I've noticed is the filling degrades relatively quickly, and after about a year it loses a lot of its volume and doesn't hold its shape as well, so you'll need to replace it. The bright side is that it's fairly cheap, and entirely biodegradable.
Surly there exists some artificial material that perfectly mimics the properties without degrading.
I'd always prefer a biodegradable and renewable material that I have to replace every few years over an artificial one that'll be around forever in some form. Not everything needs to be made out of petroleum
Just cos something is around forever doesnt mean its bad. I mean rocks exist practically forever. If plastic didnt disrupt ur bodies chemistry then there really wouldnt be much problem letting it exist in the environment forever.