Hay bale

A bale is a block of compressed organic material (hay or straw), sometimes physically bound together.

In the SCA

Hay bales (they may actually be straw but are nevertheless called hay) are used to form representations of walls, or borders of any sort (for example, the edges of a bridge). Bales are used because of ease of acquiring, weight, and relative harmlessness (it is not uncommon for fighters to be knocked into or over a bale).