The term 'scarecrow filling' refers to the material used to stuff a scarecrow. The most common material used is STRAW, which is a five-letter word. STRAW is a byproduct of grain harvesting and is made up of dried stalks of cereal plants such as wheat, oats, barley, and rye. It is often used for animal bedding, mulching, and packing material. STRAW is also used in the construction of buildings, furniture, and baskets.