The Shroom is the middle-brother of the shroom family, you will typically find these roaming near and in the Mushroom Forest. They are more powerful & give more loot than the Baby Shroom, but still are dwarfed by the Elder Shroom. When on low health, they can release toxic fumes which linger for a short bit.
The Poisoned Shroom is a variant of the Shroom, having a higher level and more health. They can only be found in the Mushroom Grotto. They release toxic fumes as their only method of attacking.