Nightlock

Nightlock berries are the poisonous berries that Katniss uses to allow both her and Peeta to win the 74th Games. Foxface died after consuming them during the Games. Katniss's father taught her that the berries were poisonous when teaching her about edible plants and berries in the woods.

Their name is derived from the toxic nightshade and hemlock, both extremely poisonous plants.