The Red Berry is an item in Paper Mario.
This item restores five points of Mario's Heart Points. It can only be acquired by smacking a single tree in Flower Fields with a Hammer. This tree is located in the area of Flower Fields with Petunia.
In addition to being a healing item, Yellow Berries can be given to the Yellow Flower guarding the yellow gate in Flower Fields. This path leads Mario to Posie, a plant who has fused her roots with a Crystal Tree.