Please stop calling it Mothers' Day if you are on the eastern side of the Atlantic. Over here it is Mothering Sunday. It's those damn Yanks who will call it Mothers' Day!
And in case you don't know how it came about, it all started, so it has been said, when servant girls were allowed a day's holiday to visit their mothers whom they would not otherwise see as they were expected to work seven days a week.
Well, that's the story; believe if you will.
Fathers' Day, on the other hand, was invented by a greetings card company!