Mushrooms in The Father Thing

When reading "The Father Thing" I became curious about the selection of using mushrooms in the description of the cocoons.  Mushrooms are natural, however they are not naturally found growing in abundance in a backyard.  The mushrooms seemed to serve a sinister purpose. Mushrooms are not beautiful like other natural plants, like flowers, and are actually not even considered plants.  Mushrooms are from the fungi kingdom and are more closely related to animals than plants.  I found that the mushrooms were appropriate for the bed of the cocoons because of the evolutionary closeness to humans and their unique function: decomposing.  It is interesting that the mushrooms are the source of decay and death, but they are in a sense bringing to life these strange creatures that eat the bodies of humans and leave only their skin left behind.  The mushrooms symbolize evil and death in this text because they are cultivating these evil "things" which cause death to the humans.  The unique pairing of life and death created by the mushrooms pulls the reader into a distorted sense of reality.  Mushrooms are supposed to cause rot and decay, and yet they are giving life to the "things."  The laws of nature don't apply as they should, sending the readers into a supernatural world.