On the 3rd chapter, one of the missions you'll be asked to complete 
is the old woman's mushroom gathering hunt. To receive the entry pass 
for this mission, you must gather a total of 30 mushrooms from either 
Tomb Pass or Maneater Road; that means getting every single one on the 
stage without dying in a very stict time limit. Use this trick to 
guarantee you get 30 mushrooms--kill yourself until you're on your 
last life. Then go collect mushrooms in one of the 2 stages. Die once
more, and select CONTINUE from the Game Over screen. You'll be back on 
the world map. Now enter the OTHER stage. All of the mushrooms you 
collected from the first stage will still be there, and you can easily 
complete your collection and return to the old woman for the pass.