uguet are sold everywhere in France on May Day, since it can be sold without a permit and free of taxation that day.
In France, Lily of the Valley is known as, "porte-bonheur"--literally, "bringer of happiness". I know it brings happiness to my #1 daughter. May is the month of her birth and Lily of the Valley is her birth flower, and although her middle name is Rose, she has always been very fond of Lily of the Valley.
Legend has it that King Charles IX received a sprig of Lily of the Valley as a lucky charm so he gave it to the ladies of the court every year on May 1st. When a lady receives a sprig of lily of the valley, she is supposed to give a kiss in return.