1. Cotton – grows on cotton plant
  2. Viscose – comes from Bamboo
  3. Wool – from sheep /goats n few other animal fur/hair
  4. Silk – from silk worms

all of the above are 100% natural product , there can be few more.

Although most of the products we buy comes in blended fiber like PolyCotton, Polywool, PolyViscose etc. where Polyester is blended to give natural fiber more strength and reduce the cost.