There are thousands of polypore species, so it is impossible to clump them all into one broad statement of edibility vs. non-edible. Most polypore mushrooms aren't toxic but also aren't enjoyable to eat because they are tough or just too small to bother with. However, there are also some that are poisonous, so, as with ALL mushroom identification, you must identify the specific species to know whether it is edible or not.