catch a whole bunch of paras or parasect. Occaisionally they will e holding either small or big mushrooms, it depends on the pokemon. They are used for re-learning pokemon moves so catching lots of paras(ects) isn't a waste of time, even if you have to fill like an entire box full of them. If you don't want to keep them (duh) then just release them
Paris, the little creepy crawly thing in the 'rock tunnel' has a chance of having it as an item when you catch it.
On two island his house in next to the game corner.
Capture a paras in Mt.Moon and take it from it.(some times it may not have it)
use your firered or leafgreen and catch parasect it should be holding a big mushroom if not try again and when you get one give it to a Pokemon and transfor it to pal park.
You can. Island 2 on Leaf Green, there is a man that will teach your Pokemon moves for 2 tinymushrooms or 1 big mushroom.
be more spacific
Catch a bunch of Paras. They always hold tiny mushrooms. And Parasect also holds a tiny mushroom.
You have to catch Paras and Parasects because they carry big and tiny mushrooms
Yes you can trade leafgreen version Pokemon to another leafgreen version.
You can catch PARAS and half of the time they should have a tiny mushroom it's evolved form has big mushroom. You can also teach one of your pokemon Thief or Snatch and it saves time and poke balls.
if you have found a tiny mushroom, or a big mushroom, you can use that to teach new moves to your Pokemon. the move tutor is either in Fuchsia city, or Lavender town. you will need a big mushroom, or 2 little mushrooms. you can get them by catching either paras, or parasect.
you have a very little percentage of randomly catching it in the wild -you got to get lucky