Natural wool, surely, has become all the rage again.
I used to wear my granda's old woolen vests for mountaineering when it was deeply unfashionable and everyone was in plastic. Although I am out of touch, I think wool has made a comeback as a 'perfect' material, though it's probably called Special Organic Insulation Fibre or something and costs 5 times what it used to.
It probably doesn't scratch any more. It stays warm (heats up) when wet, is fire resistant, lightish, renewable, long lasting, biodegradable....
and you can probably get it in second hand clothes shops, still in nearly as good condition as the day it was made, 50 years ago.