from National Geographic:
…In the postwar years Jarvis and other women organized Mother's Friendship Day picnics and other events as pacifist strategies to unite former foes. Julia Ward Howe, for one—best known as the composer of "The Battle Hymn of the Republic"—issued a widely read "Mother's Day Proclamation" in 1870, calling for women to take an active political role in promoting peace…
"Mother's Day," Not "Mothers' Day"
…Anna Jarvis never had children of her own, but the 1905 death of her own mother inspired her to organize the first Mother's Day observances in 1908.
On May 10 of that year, families gathered at events in Jarvis's hometown of Grafton, West Virginia—at a church now renamed the International Mother's Day Shrine—as well as in Philadelphia, where Jarvis lived at the time, and in several other cities…
Storming Mother's Day
…Anna Jarvis's idea of an intimate Mother's Day quickly became a commercial gold mine centering on the buying and giving of flowers, candies, and greeting cards—a development that deeply disturbed Jarvis. She set about dedicating herself and her sizable inheritance to returning Mother's Day to its reverent roots…