Mister Mushroom

Mister Mushroom is a talking mushroom found through various locations in Hallownest after the player has progressed past a certain point. His babbles can be heard from a distance, guiding the player to his location. Finding him in all seven locations rewards the Passing of the Age achievement and a secret cutscene after the player has beaten the game.

Riddle Tablet
The Riddle Tablet is a glowing glyph in a secret room at the bottom of Kingdom's Edge. When the player reads it with the Spore Shroom charm equipped, the tablet reveals a poem, which gives hints to the locations where Mister Mushroom can be found.

Locations
After reading the tablet, Mister Mushroom can be found in 7 different locations. Each one must be visited in the order described on the tablet.
 * 1) Fungal Wastes
 * 2) Kingdom’s Edge
 * 3) Deepnest
 * 4) Howling Cliffs
 * 5) Ancient Basin
 * 6) Fog Canyon
 * 7) King’s Pass