The Collaborative International Dictionary
Malcolmia maritima
mahon stock \ma*hon" stock`\ (Bot.) An annual cruciferous plant with reddish purple or white flowers ( Malcolmia maritima). It is called in England Virginia stock, but the plant comes from the Mediterranean.
Wikipedia
Malcolmia maritima
Malcolmia maritima, Virginia stock is a popular annual garden plant from the family Brassicaceae. A beautiful and profusely flowering annual, it is probably one of the easiest of all plants to grow. Growing to about 6-12 inches tall (15–30 cm), it makes a mass of pink, purple and white fragrant four petalled (cruciform) flowers. It is native in Greece and Albania and may be naturalized elsewhere in Mediterranean Europe where it occurs in maritime sandy habitats and in waste places.