TEXT: ASSAULT OF THE MUSHROOM-MEN
  Assault of the 
  Mushroom-Men
  A Swords & Wizardry Encounter
  A cavernous encounter with creatures that just keep coming!
  REFUGE
  The players have sought refuge for the the night in a 
  spacious cave they discovered just as the rain began to 
  violently come down. Although free of any signs of animal 
  life, the cave is teeming with vegetation. Thick moss carpets 
  the floor and climbs up the rounded walls and clusters of 
  fungi, some edible, cover various sections of the cave. Also, 
  long discarded items (utensils, bed roll, an old pot) attest to 
  other wanderers having used this cave as a refuge in times 
  past.
  THE GREEN ORB
  The last traveler to seek refuge in the cave was an elderly 
  magic-user. The wizard was carrying with him a strange 
  green orb which he sought to take to the elves of Mistwood in 
  hopes that they might discern the orb's properties. 
  Unfortunately, old age claimed the elderly wizard that night 
  and the orb remained within the cave, crawling moss 
  eventually covering the green stone and hiding it beneath a 
  soft green canopy.
  The reason the wizard sought the aid of the elves regarding 
  the green orb was because of a peculiar ability the orb would 
  manifest. At random times, the orb would flare with a brilliant 
  green light, the viridian rays of the flare endowing the nearby 
  vegetation with sentient life. The orb could also affect 
  physical changes upon the neighboring flora, at times 
  endowing plant matter with a human-like anatomy. 
  Unfortunately, the plants which sprang to life under the orb's 
  rays were not always benevolent, often wrecking great havoc 
  after their transformation.
  It was decided that the elderly wizard would take the orb to 
  the elves. Wise in the ways of nature and magic, it was 
  hoped the elves could find a way to master the green orb, 
  stifling its more destructive effects.
  UNDER THE ORB'S VIRIDIAN RAYS
  Sometime during the night, the orb will flare with a brilliant 
  green light. Anyone awake or on watch has a 65% chance of 
  being surprised by the sudden flare of light. This first flaring 
  of the orb will give life to the carpeting moss at the cave's 
  entrance. Quickly (in 1 combat round), the moss will crawl, 
  grow, and expand to cover the entrance, forming a mossy 
  wall to trap the players within. The players will need to "hack" 
  their way through the moss-wall in order to exit the cave. 
  Treat the moss-wall as having a AC of 9 [10] and 60 hp. 
  When the moss-wall is reduced to 0 hp (or less) it will shrivel 
  back from the entrance, allowing the players to exit. 
  As soon as any of the players begin cutting through the 
  moss, the orb will flare a second time, transforming one of 
  the mushroom clusters into 1d6 Mushroom-Men. The 
  transformation take but 1 combat round to complete. Should 
  the players defeat these mushroom-men (along with any 
  subsequent mushroom-men brought about by way of the 
  creatures'  spores), the orb will flare once more, creating 
  another 1d6 mushroom-men out of another cluster. The only 
  way to halt further flaring from the orb is to destroy it.
  Detect Magic may me used to quickly locate the orb. If 
  Detect Magic is unavailable to the party, the players must 
  rely on a simple search of the cave. For GMs wishing to rely 
  on the dice for finding the orb, the task is of average difficulty 
  (50% or 1-3 on 1d6). It will take a few rounds to carefully 
  release the orb from the binding moss. Simply striking the 
  fragile orb will destroy it.
  THE AFTERMATH
  Destroying the orb will only prevent further transformation of 
  the surrounding flora. Anything created  before the orb's 
  destruction remains in place.
  Keeping the orb, or fleeing with the orb intact, will see the 
  players constantly forced to battle whatever greenery the 
  orb's erratic flaring brings to life. These adversities caused by 
  the orb need not not be limited to anthropomorphic foes (like 
  the mushroom-men) but can include things like falling 
  branches, trees moving to block the players' progress, vines 
  or bushes slowing the adventurers' movements, etc.
  ANTAGONISTS
  Mushroom-Men: HD 3, 2, or 1; AC 5[14]; Atk Fist (1d6) or 
  weapon; Save 14, 16, or 17; Move 12; CL/XP 5, 3, or 1/240, 
  60, or 15; Special: Spores.
  SPOILS OF VICTORY
  No treasures are gained from this encounter. The players 
  may decide to keep the orb but as stated above that course 
  of action may prove costly.
  NEW CRITTERS
  MUSHROOM-MEN
  Armor Class: 5 [14]
  Hit Dice: 3, 2,1
  Attacks:  Fist (1d6) or weapon
  Saving Throw: 14, 16, 17
  Special: Spores
  Move: 12
  Challenge Level/XP: 5, 3, or 1/240, 60, or 15 XP
  Standing 4' in hight, mushroom men resemble humanoid 
  mushrooms endowed with both arms and legs. Mushroom 
  men are usually found in natural caves, caverns, and 
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  ASSAULT OF THE MUSHROOM-MEN
  underground passages.
  Mushroom-men are initially created by magic. Once given life 
  through magic they reproduce by way of spores. When a 
  mushroom man dies (0 hit points or less) it releases 1d6 
  spores which rapidly (within 1d4 rounds) grow into 
  mushroom-men of 1 HD lower than the parent mushroom 
  man (1 HD mushroom men do not produce spores upon 
  death). The spores have 2 hit points (before becoming fully 
  formed mushroom-men).
  2
  
SOURCE: textdata/thevault/Swords & Wizardry (osr) [multi]/SnW 1e & 2e/Adventures & Settings/SnW - Assault of the Mushroom Men.pdf