Possible Clues:

• Poisonous growth contemptible people saw, for example
• Plant akin to mushroom
• Poisonous fungus
• Fungus beginning to develop in brown rings by lake
• Forest dweller with a cap
• Chase after stinkers -- a kind of fungus
• Breakfast including last of lard, ladies up for something inedible?
• Fungus from mouldy old toast — brown in the middle
• Device needed to renovate a small pad, perhaps
• Fungus initially detected in brown bread John sent back