LDS don't currently practice it, and this may be something missionaries who go looking for new members probably do avoid in telling potential members...but mormons very well believe in the practice of polygamy. It is indocrinated in their very own sciptures in D&C 132. They don't practice it. That's true, but as a young teenager when I first heard of our polygamist hitory I remember asking why God would command something then and not now (which I was thankful for, because I didn't wanna practice polygamy), and remember being told that the church did cease to practice polygamy on this earth, but does expect to continue the practice in the afterlife. That is why when a married woman dies, a man can mrry another woman in the mormon temple for all time and eternity, and he will have 2, 3, or 4 or however many wives he outlives and marries in the temple in heaven and they will all be his wives in heaven...but a woman can only marry one man in the temple for all time and eternity. So if she outlives her husband, she can remarry, but not in the temple and for time and all eternity...she can only marry til death do them part. In heaven she will only have one husband. These are beliefs you probably won't hear from the missionaries. I guess they save these beliefs for when the member actually gains a testimony of the church.
To answer your question though, no I have not been excommunicated. I am still a full member of the church of jesus christ of latter day saints. I don't practice polygamy because the church doesn't...but I do expect for it to ressume in the afterlife, which is what brings me here. I wanna be prepared for it, including meeting people who live this way now...