Eating the bedding is just fine. Straw won't have as much nutritional value as various hays but it is fiber and it does break down in the bedding pack so that it becomes digestible. Think of pigs out in the wild, a lot of what they eat is rotting wood, forest floor material, etc as well as grasses and other fodders. Instead of straw we use a layer of wood chips and then top it with hay because the hay is more digestible and nutritious than straw. Hay is also cheaper and easier to come by where we are than straw - this varies regionally.
Make sure they get plenty of fluids - freely available water.
-Walter