In settings where there are long established underworld thief, criminal and otherwise ne'er do wells there is going to be a system of heraldry associated with those who live in and rule from the shadows.
Giant mushrooms the size of trees. The stems and parts of the caps can be used in construction, and only the gills are soft enough to eat. An entire fungi-forest can grow in a matter of days, provided the correct conditions. Most fungus trees last about a month before collapsing, but not before a new generation sprouts to provide shade for the next spores.