More mushrooms:
When mushrooms appear, collect them, leave the screen, then
return to collect them again. Repeat this until they no longer appear.
Large med-kit:
When fighting a Deadite or Hellbilly, turn on your chain saw and
slash at them. After a few hits Ash should jam the chainsaw into them
and keep it there. Then, use the ax and hit the Deadite while your
chain saw is still in them. When they die, they will usually leave
behind a Large med-kit. You can also use the other weapons instead of
the ax, but it just wastes ammunition.