I ran across this guy yesterday while scouring thru this zone. If you come in from the Echo side , this fungi is a ways north ,near the entrance to the shik nar tunnels. He is to the right of the entrance , up against a wall, situated in between two lotus plants (perma rooted) and not too far from a mushroom camp.
A few things to note. You can agro the lotus from a distance , but they are permarooted. If you approach one to kill it, you will agro the Shuddering Fungus. So unless your able to kill at least one of these from afar , expect one, if not both lotus' to cast on you during your fight with Shuddering.
Also , try not to back up while fighting him. Your near a mushroom camp, and they will add.
The Shuddering himself is an easy fight . I solo'd him as a lvl 70 paladin , but the adds almost killed me. He dropped A Sturdy Mushroom Stem when i killed him.
Magic Item .
Not Lore.
Not No Drop.