I am running a group through ROTRL and they are currently 13th level. They are in the middle of a higher level dungeon like section and are thinking of using Fairy Ring Retreat for rest. The entry point "looks like a circle of toadstools encircling a 10 foot square" - wouldn't this be highly noticable? What are the chances the big bad will know the significance of the ring of toadstools and is there any way the party could hide the ring?