Photo credit: http://www.webmastergrade.com/top-10-happy-mothers-day-greeting-cards/
Cut and pasted from the BBC Religions website here:
Mothering Sunday is the fourth Sunday of Lent. Although it's often called Mothers' Day it has no connection with the American festival of that name.
Traditionally, it was a day when children, mainly daughters, who had gone to work as domestic servants were given a day off to visit their mother and family.
Today it is a day when children give presents, flowers, and home-made cards to their mothers.
Mother and Child (detail from The Three Ages of Woman), c.1905 by Gustav Klimt
Photo credit: http://www.allposters.com/-sp/Mother-and-Child-detail-from-The-Three-Ages-of-Woman-c-1905-Posters_i825888_.htm
History of Mothering Sunday
Most Sundays in the year churchgoers in England worship at their nearest parish or 'daughter church'.
Centuries ago it was considered important for people to return to their home or 'mother' church once a year. So each year in the middle of Lent, everyone would visit their 'mother' church - the main church or cathedral of the area.
Inevitably the return to the 'mother' church became an occasion for family reunions when children who were working away returned home. (It was quite common in those days for children to leave home for work once they were ten years old.)
And most historians think that it was the return to the 'Mother' church which led to the tradition of children, particularly those working as domestic servants, or as apprentices, being given the day off to visit their mother and family.
As they walked along the country lanes, children would pick wild flowers or violets to take to church or give to their mother as a small gift.