Hogs Hair is the finest filling, which comes from Cattle and Pigs. The longer and curlier the hair the better the quality.
Cheaper than hair is Black Fibre, made from Algerian Grass. Usually dyed black but sometimes left green. The black keeps its curl better.
Coconut Fibre or Curly Coir, comes from the outside of the coconut. The longer the fibre the better the quality.