Paper Mario: The Thousand-Year Door Tips

Poison mushrom heals you
If you make a Poison Shroom from Zess T. (a Slow Shroom and an Inky Sauce), the effect will poison you. If you have the Feeling Fine badge on, however, it may do one of 2 things:
1) Heal you to max
2) Cut your HP in half
Be wary when doing this.