Beneath The Forest

Beneath the trees, where sunlight never reaches and few green plants grow, mushrooms (and decay) flourish in the ever-damp soil, surrounded by darkness. Step carefully, there could be traps. (yes, of course this was inspired by the Underdark. Not a forest floor, but literally *beneath* the forest, underground. Think damp caves with scant vegetation, and no "forest" smells like leaves or evergreen needles) No actual "mushroom" or decay type notes.