Capers

Capers - [Capparis spinosa, also C. sicula, C. orientalis, and C. aegyptia. Australian "wild passionfruit" Capparis spinosa subspecies nummularia all of genus Capparaceae]
Caper buds

Capers are most known to Americans as pickled flower buds used as a flavoring element and garnish in salads, sauces and martinis. In the Mediterranean region where they are native fruits are also pickled as are the leaves The photo specimens of pickled flower buds came from two bottles, both qualifying for the top "Non-pareilles" designation, though the large ones barely squeeked by at the 7 mm / 0.276 inch maximum. The small ones were typically 4 mm or less.
[Parent - Brassicales Page]

Capers are graded by size with the smaller considered more desirable. Sizes are:

Non-pareil (up to 7 mm)
Surfines (7-8 mm)
Capucines (8-9 mm)
Capotes (9-11 mm)
Fines (11-13 mm)
Grusas (14+ mm)

Nasturtium buds are sometimes substituted for capers, having a similar taste. They are usually in the larger sizes.

Fruit and Leaves
Ripe Fruit Caper fruits (caperberries) grow to about 2-3/4 inches long and are ripe when they split open exposing white flesh and black seeds (the pictured one is just a bit past its prime). The leaves are thick and succulent lending themselves to pickling like the buds. Fruits are are also pickled and served as appetizers, particularly in Greece. Photo by Florian Prischl / Wikimedia Commons - distributed under license Creative Commons Attribution-Share Alike 3.0 - attribution required, notification requested.