Behold the handmaid of the Lord. Let it be to me according to your word. (Luke 1:38)
In secular terms, Lady Day is also the "first of the four traditional Irish and English quarter days," the "four dates in each year on which servants were hired, and rents and rates were due." The other quarter days are Midsummer Day (June 24), Michaelmas (September 29), and Christmas (December 25).
I think the Botticelli Annunciation (above) is particularly effective because of the sweeping line from the angel Gabriel, clearly making obeisance, up to the Virgin, who is bending forward regally, as a queen would to a kneeling subject. Too often Mary is portrayed as a passive recipient of the Holy Ghost. Here she is gracious, confident, welcoming, and Gabriel, rather than looming over her as he does in many portrayals, is clearly the one who is in awe. As in the Anglican hymn "Ye Watchers and Ye Holy Ones," she is seen to be
higher than the cherubim,
More glorious than the seraphim.
I am also rather fond this modern Annunciation by John Collier. The idea of Mary in Oxfords getting what looks to be an angelic floral delivery in the middle of suburbia pleases me no end.