In the run people use dirt, sand, wood chips, wood shavings, straw, hay, grass clippings, and dried leaves to mention a few.
In the coop people use wood chips, wood shavings, straw, hay, dried grass clippings, dried leaves, dirt, sand, and linoleum to mention a few.
In nests people use wood shavings, straw, hay, dried grass clippings, carpet, Spanish moss, plastic or cloth feed bags, and rags to mention a few.
Some people turn their run floor or coop floor into a compost pile. Those can get really wild.
Your climate, facilities, drainage, and management techniques play a part in these selections. I like them to be inexpensive and available.
My run is dirt. The coop floor is dirt topped with wood shavings. For my nests I cut long grass from areas I don't weed eat or mow and dry it.