Fungus grows in dark, moist places, and its appearance in a dream may signal something that has grown and spread within the subconscious, such as negative emotions It may also point to disease in the body.
To see fungus in your dream represents negative emotions that are expanding and growing in your unconscious. You need to find a productive way to express them before it grows out of control. In addition, if the fungus was growing on your body, you may want to look up that body part for additional meaning and insight.
Dreams of fungus represent that you have been neglecting certain aspects of your well being. Perhaps you have been indulging in negative, -deprecating thought forms or relationships. This dream is also showing you that life continues to emerge even from decay. Such dreams are about the life/death/life cycle, the fact that nothing ever dies, and that there is always a growth opportunity hidden with all things that appear to be maligned.