Capers are the unripened flower buds of the plant Capparis spinosa.
The caper plants are native to the Mediterranean area and some parts of Asia. 
Brined or dried, capers are valued for the burst of flavor they give to foods, a flavor described as lemony, olivey, and definitely salty.

They make fun additions to a great variety of recipes, including fish dishes, tapas, pasta, and sauces. 

You can find capers in different sizes and if you leave the bud on the plant, it will grow out to become a caperberry which is also delicious in many dishes.

Sizes:

8-9mm
9-11mm
11-13mm