Second Sunday in May.
Day set apart in the US, UK, and many European countries for honoring mothers. It is thought to have originated in Grafton, West Virginia, US, in 1908 when Anna Jarvis observed the anniversary of her mother's death.
In the US, Australia, and Canada, Mother's Day is observed on the second Sunday in May; in the UK it is known as Mothering Sunday and observed on the fourth Sunday of Lent.