Willow Down

Willow Down is a down like product made from the oily layer of hairs that covers the flowers of certain willow trees.
  Willow Down is expensive as it can take over two hundred trees to produce enough to fill a pillow. The harvesting process is also very likely to harm the tree. It takes the utmost care and experience to harvest Willow Down without damaging the flower. A tree that had its flowers damaged before blooming will not produce new flowers from the same branch in the coming year. Even if the flower is unscathed from harvesting, it is now exposed and is prone to damage from wind or insects. To protect the flower harvesters cover the flowers with so called "leaf crowns". Leaf crowns are meant to cover but not touch the flower but even if they touch it is not a big deal as long as the crowns are made from the leaves of the same tree as the flower.
  When properly processed and taken care of, Willow Down will last for centuries.
  Some Wood Elf cultures have made Willow Down harvesting and care a part of the upbringing of children. A child will likely make its own Willow Down pillow and transplant it into bigger pillows as the child matures.