Fleur-de-lis is French for flower lily and the well known stylized design in its countless variations has been used as a decorative design or symbol for centuries. It is particularly known as French symbol even though it has never been adopted officially by any of the French republics.
It is an extremely popular design for Christian embroidery too. Michel Pastoureau, the historian, says that until about 1300 the fleur-de-lis was found in depictions of Jesus, but gradually they took on Marian symbolism with the three petals of the design reflecting an association with the Holy Trinity, and the band on the bottom symbolizing Mary. Other scripture and religious literature in which the lily symbolizes purity and chastity also helped establish the flower as an icon of the Virgin.
No matter how you use them, fleur-de-lis designs make for beautiful and instantly recognizable embroidery.