Possible Clues:

• Fungus in a smelly plant left to wither
• A fish, I see, like a mushroom
• Fungus that could be rolled into a cigar
• A plant left out gets fungus
• That's a fish, I see, with mushroom
• Fungus, eg, mushroom
• One must be fly to spot this fungus as poisonous!
• A fish, I see, will provide fun with Gus
• Kind of mushroom
• Fungus with gills on the underside of the cap