Fungus Garden is the first multiplayer instance in the game. Technically, the tutorial is considered an instance, but it is not repeatable and solo-only. Fungus Garden does not have any real level requirement because all mobs are non-aggro.
Fungus Garden can be found North East of Pioneers Colony in Howling Mountains, inside a cave in the mountains. A NPC outside gives you a daily quest you can repeat to be completed inside Fungus Garden.

The mobs found in this instance are listed below: