Field Dungeon Key

 is a key.

Obtaining

 * Dropped by
 * Blue Larva
 * Crab
 * Dark Rose
 * Demonic Rose
 * Evil Dandelion
 * Moskito
 * Mush Mush
 * Red Scaraleaf
 * Vulnerable Mush Mush
 * Wild Sunflower
 * Crafted by a Handyman (Lv. 1) from

Uses

 * Access
 * Field Dungeon
 * Used in the craft of
 * Key to the Fungus Dungeon