Miracle Fruit
Synsepalum dulcificum
a.k.a. Miracle Berry
A relatively tasteless berry with an amazing side-effect. After eating one miracle fruit, sour things will instantly taste sweet. Eating even the sourest of lemons, one will taste only sugary sweetness. The effect lasts an hour or two. The miracle fruit is a remarkable natural sweetener that is virtually unknown to much of the world.

Berries are eaten fresh. Africans sometimes use the fruits to improve the taste of stale food. Fruits are being investigated as a possible source for a natural food sweetener.