I stumbled across this thread again quite by accident this morning and thought I would try to answer some of the questions that have been posed in this thread. A few years ago, I did a book about another Iron County cemetery and while doing research in the Missouri Death Certificates database came across an African-American (Willis Cole) being buried at the Iron County Poor Farm or the County Farm as it was called.
Rick Walker, the creator of the Find-A-Grave listings for the burials at the County Farm Cemetery, researched the same database and other sources to come up with the other names listed. I then took Rick's list and checked it against a couple of other sources, added a couple more names and published a paper in the newsletter of the Iron County Genealogy Society.
If anyone is interested in getting a copy of the article emailed to them, you can contact me at firstname.lastname@example.org
and I will send you a pdf file with the article. Marcus is still not on that list and I suspect that, based on is death certificate, that we was taken to Madison County (though death certificates are sometimes wrong too).
President, Iron County Historical Society
Recording Secretary, Iron County Genealogy Society
Education Director, Missouri State Genealogical Association
and Happily Retired, though my wife will tell you that I am unemployed