Traditionally, on the May 1st in France is given lily of the valley as a present.
In the language of flowers, lily of the valley means 'return of happiness.' We give it on the first of May to bring happiness.
This tradition goes back to the Renaissance era - on 1 May was given a twig to dispel the curse of winter.
In 1560 King Charles IX, during his visit to the region of Drôme River, received a sprig of lily of the valley. He liked the gesture and the next year he gave one to the ladies of the royal court to bring them happiness.
May 1st is also the Day of labour. Giving lily means that you wish happiness, but you wish also work. On this occasion, on May 1st each can sell lilies of the valley on the street, professional florists or individuals - without observing the formalities or pay tax.