I love my mother but Mother's Day, not so much. Bitch. Ph.D. (who I must note is a mother herself) has a good, if brief, look at the history of Mother's Day
and some links. I liked this bit:
It's a political holiday, founded by political women, who viewed motherhood as a political institution. Specifically, Mother's Day was originally a pro life holiday in the true sense of the word: it claimed mothers as life-givers not in order to deny them rights over their own bodies, but to advocate against killing their sons in war.