Sunflowers were first domesticated over 5,000 years ago by the peoples of southern North America.  They are grown for their oil-rich seeds, and are also a traditional staple food crop.  All parts of the plant were used: petals to make a golden dye, stalks for fibres and leaves and roots used in traditional medicines.  New research also indicates that growing sunflowers can help to decontaminate soils by absorbing radioactive ions and heavy metals.  According to the James Wong (‘The Many Uses of Sunflowers,’ The Garden, RHS Feb 2013, p.17)

Hhmmnn….  Makes me think they might be a good plant to grow as a preliminary ‘crop’ of flowers when preparing new allotment beds near railway lines….