"The Whisperer In Darkness", first published in Weird Tales, August 1931.
This is the the twenty-second entry in my read-through of the commemorative edition of Necronomicon: The Best Weird Tales of H P Lovecraft.
While reading this story again, I have in the back of my mind, the gaming supplement Delta Green , which re-imagines the Fungi of Yuggoth through the lens of contemporary UFO mythology. The supplement takes in Majestic 12, Roswell, greys, Project Blue book and secret government UFO files and places them in the context of decades of contact with the Fungi to great effect. Even allowing for the cleverness of Delta Green, it's surprising how close the fit is.