Henry Mayhew's 1861 London Labour and the London Poor has; "The first coster cry heard of a morning in the London streets is of 'Fresh wo-orter-creases.'"
Eliza James 'The Watercress Queen', went from hawking cress as a five-year-old on the Birmingham streets, to owning a vast empire of watercress beds in Surrey and Hampshire, a near-monopoly of the London commercial trade and coining the trade name 'Vitacress'. On her death in 1927, the Daily Mirror described her life "as one of the most wonderful romances of business London has ever known."

Watercress beds
Image: Mark Percy
http://watercress.co.uk/about/historical-facts/