Wool

Wool is a bio-material fabric that comes from sheep. It is used by both humans and Smurfs for various functions.

Empath: The Luckiest Smurf stories
Wool in the EMPATH: The Luckiest Smurf story series is often gathered by Wooly the village sheep shearer and made into cloth by Weaver for use by Tailor in the making of clothes and other items made of cloth.