For the U.S.A. that is. Mother’s Day isn’t the second Sunday in May everywhere. Many countries celebrate mothers on International Women’s Day (March 8), the U.K and Ireland still celebrate it on Mothering Sunday, France and other French-speaking countries honor moms on the last Sunday of May, and in Mexico, it is always celebrated on May 10. According to online factoids, Mother's Day cards account for $813 million in sales. Hallmark claims that 113 million cards are exchanged making Mother's Day the third-largest card mailing holiday. Just FYI, everyone.