Mormon "prophets" actually had two decrees vs. plural marriage: 1890 (Woodruff) and 1903 (Smith). B. Carmon Hardy in his book, Solemn Covenant, documents a few hundred specific additional plural marriages in his appendix -- these occurring between 1890-1910.
IOW, polygamy just went underground a bit more -- but was still solemnized by Mormon leaders...especially during the years of 1890-1903...in the 1900s, two Lds "apostles" were ex-communicated for still legitimizing polygamy. And it wasn't until this 1910 enforcement letter went around that Mormon leadership took seriously any line in the sand on polygamy.
So when people try to tell you Mormonism ended polygamy in 1890, they're "snowing you" -- or they just don't know.
Even in 1910, Mormon leadership didn't address existing polygamists. Some of those polygamous unions didn't die out until the early 1960s.
Also, if Mormons tell you or imply that polygamy is past tense, they indeed are snowin' you.
#1...they believe marriage is eternal...so all these 19th & 20th century polygamists, they think, are still practicing polygamy...it's just colonized to somewhere near Kolob.
#2...Mormon policy dictates that even Mormons living today can become eternal polygamists. All they need to do is to serially marry more than one spouse...and be sealed to each for eternity.
God created ONLY Adam and Eve.
Not Adam and Eve and another Eve and another Eve, etc.
Or Utah. With magic underpants, anything is possible.