Straw, pine bedding, sand (as long as it doesn't freeze where you are), are common. Pine needles could work as part of the material, but pine needles aren't absorbent. If you use them to bulk up shavings or break up the sand that could work, I suppose.
Where are you located? someplace warm or that freezes in winter? My neighbor has chickens and when he saw our coop that we are building (raised off the ground) he wondered why we weren't using a wire/open floor so the droppings could just get scratched into the ground below by the chickens when they were out and about during the day. It is too cold here to have an open bottom to the coop, but I would imagine could also be a solution if you live someplace warm. does your coop have a dirt floor? if so, many on here are fans of the deep litter method (aka "DLM") - its kinda like a compost pile in your coop - varied organic material that breaks down over time and helps with odor, etc.