Straw helps keep you warm if you go deep in the haystack. Cotton balls have trapped air space so they would be a good insulator. If you glued cotton balls all over your skin, you would feel warm. If you were to go to sleep without a blanket you would feel cold, but if you went to sleep with a blanket you would feel warm. Also if you put pine needles all over your friend, in a few minutes, your friend would probably feel warm.
Straw is another insulator.
It can be used to cover plants to keep them from freezing. Snow insulates the ground. Some people make their house in a hill because dirt helps insulate. Wood chips are good for covering and insulating plants. Pine needles also insulate.