Provided are a structure and a method of forming a structure that includes a core made, at least in part, of a rice hull composition. The rice hull composition including a combination of separate, unground rice hulls; ground rice hulls; and a rice hull powder, that each have a different particle size. A polymeric binder, such as a recycled plastic polymeric binder binds the separated unground rice hulls, the ground rice hulls and the rice hull powder together.