The movie Matango: Attack of the Mushroom People is a very creepy 1963 movie in which fungus causes the transformation of humans into, indeed, Mushroom People. Google translate is no help and one search translated "Matango" into "Attack of the Mushroom People" which seems wrong to me. Google just translates it into English as "matango" which is not very helpful.
The movie is based on a turn of the 20th century short story which is called The Voice in the Night and I am wondering if the original title is somehow related to the word.
I find here: https://wikizilla.org/wiki/Matango#Name that the name is based on the name of a fungus which is called "mamadango" but this might be made up. It does make it seem less likely that the title is related to the original short story.