On the 15th March, Mother's Day was observed in the United Kingdom, Ireland and Nigeria on the fourth Sunday in Christian Lent.
Also, known as Mothering Day, the observance is meant to celebrate the role of mothers, motherhood and importance of maternal bonds in society. In some countries, it celebrated in March and some other in May. In most countries, including India, Mother's Day will be observed on second Sunday of May.
Internet giant Google's homepage in UK celebrated Mother's Day with a special cartoon doodle depicting motherhood across nature by featuring a mother swan, leopard, rabbit and human with their young ones.
However, in UK, Mothering Sunday has got transformed into the tradition of showing appreciation to one's mother contribution to the family and society. The holiday is recognized in the original historical sense by most churches in the country to pay homage to Mother Mary - the mother of Jesus Christ.
In UK, the Mothering Sunday had been celebrated for centuries with the tradition of preparing and eating cake on that day. However, due to commercialization of the observance, children buy gifts of chocolate or flowers along with cards for their mothers as a way to thank them for their contribution to the society.
I think, Robert A. Heinlein has rightly described motherhood by saying, "Being a mother is an attitude, not a biological relation."