This doesn't answer the question, but I have some related notes:
* It looks to me like there's a certain amount of consistency in the records - it's "Marinda", not "Miranda".
* I don't know if you've noticed this, but there's a very special thing about the 1925 Iowa census: On the second page (and you need to know that there's a second page to go look at) it give the person's PARENT'S names, as well as where they were born.
For Lone Knoebel, it says her parents are "James Olliver" and "Marinda Olliver", both born in OH. I get the impression that this is also the correct spelling for "Olliver", which might be helpful.
* Of course, having mom and dad with the same surname is suspicious, but I think it's actually real. I say that because I looked for James Oliver in OH, and found 5 or 6 of them. Some were clearly the wrong guy - there were records tracing them forward, down a different path. The one that looked the most promising to me was in Washington County (on the southeastern edge of the state).
To back up a little, it seems clear that Marinda, born abt 1840, married James - probably shortly after the Civil War (perhaps he was in it), had Lone abt 1868, and Edward died shortly thereafter, around 1869, before the 1870 census.
One thing this means is that Lone is an only child, so there won't be distant cousins out there in your DNA at that level.
Getting back to Malinda, there's a 1856 IA census with "Marinda Oliver", 19, b OH, living in Millville, in Clayton Co IA. I swear I saw her in the 1860 census in Washington Co, OH, but I can't find it again. She appears alone in these census records. I think I also ran across an "Olliver" from Washington Co who also ended up in Clayton Co. It would have been pretty easy to travel from one place to another, since they're on big rivers that merge.
* The 1870 census says Marinda is the daughter of foreign born parents, and illiterate. The James Oliver I have my eye on lived in Liberty Twp in 1860. His parents, John and Mary, were born in Hanover (which is to say, Germany). There are many other Germans in the neighborhood, so Marinda seems to fit in.