The myconids of Neverlight Grove are a peaceful people, organized into circles. Even their “hunter circle” doesn’t actually kill things, but just collects corpses of anything that dies close to the village and uses them as fertilizer. So the group’s first encounter with the myconids (other than their travel companions Stool and Rumpadump) was after they killed a Shambling Mound near the village, and the “hunters” turned up and asked politely if they could collect it. That got the group a friendly welcome to the village, and a quest to kill another monster which was attacking myconids outside the village.
I had some commercial poster battlemaps of Underdark caves, and used one of them for this fight against a Grick alpha. What I hadn’t noticed was that on the map there was a pond with treasure chests visible at the bottom. So after the fight the group wanted to lift those chests, and I didn’t want to spoil their fun and say there weren’t any. So I let them roll on the appropriate treasure table in the DM’s Guide, and they ended up with a Figurine of Wondrous Power (Ebony Fly). Nice, but not overpowered.
Back in the village the group interacted with the myconids and learned that they were split in two factions. The “normal” ones were a bit naive, friendly, and not very emotional. The others were overly enthusiastic, dancing around, and awaiting a great event for tomorrow in the Garden of Welcome. They were asked not to go to the garden so as to not spoil the surprise, so of course they went.
That resulted in several fights against infected myconids and other creatures. Ultimately the group discovered yet another demon lord, Zuggtmoy, who apparently is preparing her wedding to the “Great Body”. Various infected plant creatures serve as chamberlains and bridesmaids in some sort of perverted wedding ceremony. But it is rather obvious that the group can’t stop the wedding without fighting the “bride”, and they aren’t strong enough to tackle demon lords yet. While the un-infected myconids flee, the group decides that they should do the same, and travel on towards Blingdenstone.