公豆是一种变种的咖啡豆，指的主要是Peaberry或caracoli，而公豆只是中文的俗称。

公豆形成的原因尚未科学证实，已知生长在咖啡树树枝末端的咖啡豆较有机会出现此现象。

Peaberry, known in Spanish as caracoli, is a type of coffee bean. Normally the fruit ("cherry") of the coffee plant contains two seeds ("beans") that develop with flattened facing sides, but sometimes only one of the two seeds is fertilized, and the single seed develops with nothing to flatten it. This oval (or pea-shaped) bean is known as peaberry. Typically around 5% of all coffee beans harvested have experienced this small mutation.