It is Mothering Sunday.
In the Middle Ages in Britain parishioners would make a journey to the church that they had been baptised in - the mother church. This is where the celebrations of Mothering Sunday originate, even though nowadays most think of the occasion differently. That is due in no small part to Constance Adelaide Smith who argued for a more inclusive definition of mothers in the 1920s.
Head on over to this British Library page to read more about Mothering Sunday and its observance, and to see some wonderful illuminated manuscripts, including one of The Virgin Mary punching the Devil in the face! Happy Mothers' Day everyone!