The Memories of The Ruins of Quasqueston -- The Myconids and B1 Insearch of the Unknown By Mike Carr

 My first encounter with the alieness of the dungeons of B/X & Advanced Dungeons & Dragons first edition came in the form of  Mike Carr's B1 Insearch of the Unknown. The fungus garden within the module was stocked with Shriekers, Violent Fungus, & tended by Myconids who owned that room. My uncle was DMing and it was back around when the Monster Manual II had been released. 

Full-page advertisement for module B1 "In Search of the Unknown" appearing in The Dragon #s 22-25 (February-May, 1979) from the OSR Grimoire blog. 

We'd been through B1 before but hadn't explored all of the ruin and there was something slightly off about the ruin at this point. The monsters were getting weirder as anti nature of the dungeon started to take over the ruins of B1. The underworld of the dungeons of Greyhawk began to infiltrate the ruins of Quasqueton . And it was during this time that we had a meeting with the  Myconids as they were flanked by Vegepygmies as bodyguards. And we found out that it was the Myconids that were introducing  shambling mounds, phantom fungi, assassin vines and roperlike plant monsters
 

And this was the first time that the ecology of the dungeons

 was controlled by other far more alien races. The decay of  the ruins of Quasqueton had allowed the fungus men into this once point of civilization. And it was also the first time that my wizard thought there might be something deeply sinister within the bowels of the caves of Quesquenton. And it was when we pentrated deeper into those ruins we came face to face with the Fiend Folio's hook horrors. And again these were brought in by the fungus men. The hook horrors survived on a diet of phycomids, shriekers, violet fungi, and zygoms 

The hook horror from the classic Advanced Dungeons & Dragons first edition Fiend Folio 

The Myconids simply saw themselves as gardeners and guardians of a different ecological system. And they were acting as druids spreading the life of thier own world to abandoned systems. We later on took over  the ruins of Quasqueton after learning that there was a gateway to other worlds deep within it's ruins. And we able to make peace with the Myconids as we let them have the lower levels of Quasqueton as long as they acted as guardians for the lower levels and didn't eat any of the household. It was only much later on that we learned that they had come over from Gamma Terra. The ecology of my uncle's dungeon was never static.  
And even when the adventurer's were absent the dungeon continued to attact monsters and other horrors to it. Even when we weren't playing my uncle as the DM was playing with and tweaking the dungeons of Quasqueton.