In Ireland, Mothers Day is not celebrated on same day as in US. In Ireland Mother's Day always falls on the fourth Sunday of Lent.

A Brief History of Mother's Day in Ireland
The celebrating of Mothers Day in Ireland dates back to medieval practice when the children of poor families were often sent at a young age to work as domestic servants and apprentices to work with the rich. Once a year during Lent these poor children were given a day off to visit their 'Mother Church' or local home town parish to worship the Virgin Mary. After attending mass in their home town the children would then be able to visit their own mothers. The would pick flowers to give to their mothers. The you girls would bake special Mothering Cake on this day. After the Industrial Revolution the tradition of "Mothering Sunday Celebration" nearly disappeared as children went to work in factories.  "Mother's Sunday" or "Mother's Day" was revived after World War II in America.