Basil. The totem plant of the Greeks, and as such rarely eaten, not even for flavouring a tomato sauce or salad (that's what Greek oregano is for, after all).
Anyone with a garden or balcony is likely to have some, either the big leaf kind or 'dwarf' Greek basil in a pot or old olive oil can, as an ornamental and as a blessing to their homes rather than a culinary ingredient. Older people like to put sprigs of basil behind their ears. Priests use bunches of basil to sprinkle holy water.
The story goes that when St Helen, the mother of the Emperor Constantine, discovered the True Cross in Jerusalem, a basil plant grew nearby in the shape of a cross. So she named it vasilikós 'of the king' of heaven.
Image by Salvadonica Borgo del Chianti