5. Cashmere.
This fibre comes from cashmere or pashmina goats. The goats have a double coat, with a downy undercoat and a coarser coat of guard hairs. It’s the downy undercoat you want. The modern problem with cashmere is that the goats, when they graze, pull the entire plant from the ground, as opposed to sheep, which tear off the top of the plant. Goats can denude a pasture, which is all kinds of bad for the environment.