Capers. They grow in many places of Greece and Cyprus, where the leaves (as well as the buds) are eaten fresh in salads (if they dominate, it's a καπαροσαλάτα (kaparosalata), which is a specialty on Santorini. Sometimes the leaves are preserved in salt, too.
On the islands you may also find stewed capers, κάπαρη μαγειρευτή (kapari mageirefti) made with onions, Mavrodafni and olive oil. They are popular on Sifnos; on Santorini they sometimes serve them with fava.
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