Mattress stuffing is a material used to fill mattresses and other soft furnishings. It is usually made from natural fibers such as cotton, wool, or KAPOK, which is a silky fiber obtained from the seed pods of the KAPOK tree. KAPOK is a lightweight, buoyant material that is often used in mattresses due to its ability to provide cushioning and support. It is also hypoallergenic, making it a popular choice for people with allergies.