Medicinal uses
John Gerard seems to have been somewhat sceptical as to the efficacy of the field poppy - "Most men being led by false experiment than reason, commend the floures [flowers] against the Pleurisie, giving to drinke as soon as the paine comes, either the distilled water or syrup....And yet many times it happens, that the paine ceaseth by that means, though hardly sometimes." In other words - it seems to work but not always very effectively!
Culpepper refers to wider use in the treatment of catarrh and coughs, hoarseness of the throat and loss of voice. He also states that, "Boiled in wine and drank, the black seed stays the flux of the belly and women's courses. The poppy heads, boiled in water, are given to procure rest and sleep."
Modern uses are for the treatment of coughs, asthma, bronchitis, catarrh, whooping cough and angina as well as inducing sleep.
In his book, "The Folk-lore of Plants". T F Thiselton Dyer refers to a romantic use for the poppy when talking about love charms - "Among some of the ordinary flowers in use for love divination may be mentioned the poppy, with its 'prophetic leaf'....."
The best known reference to the Field Poppy is, though, as the flower of remembrance. In her book, "The Folklore of Plants", Margaret Baker states, "Poppy, the memorial flower, springs up quickly after soil disturbance, sometimes within twenty four hours. When the field of Waterloo was ploughed, millions of scarlet poppies grew just as they would one hundred years later in Flanders after the First World War.
William Shakespeare also makes a reference to the poppy. In Othello, Act iii, Scene 3, Iago has says
"........Not poppy, nor mandragora,
Nor all the drowsy syrups of the world.
Shall ever medicine thee to that sweet sleep
Which thou own'd'st yesterday."
Don't' ask me to explain the context....my knowledge of Shakespeare is very limited! However, clearly this is a reference to one of the poppy's medicinal uses. The reference to mandragora is thought to be to the opium poppy (Papaver Somniferum). In Shakespeare's day, and before then, the opium poppy, which is mauve, was cultivated for its beauty as a garden plant, as it is today.