Yes indeed there were lots of coal mines in and around Centerville Ia, as well across south eastern Iowa at locations like Albia, Ottumwa, Oskaloosa and all the way to Boone and beyond in the Des Moines river valley. For those who like history on these type of topics, here are some websites.
A quick search for Iowa Coal mines will lead to many, many more sites. The last active Iowa coal mine did not shut down until the mid 1980’s.
My wife’s grandfather owned a small Iowa Coal mine, which allowed them to keep the farm during the depression.
Of interest is this photo of the boxcar Charlie asked about, GRYX 1018, lettered for Empire Fuel
Here is an article the mentions the Empire coal mine. http://dailyiowegian.com/correspondents/x519470404/Mines-on-Interurban-Railroad-to-Albia/print
Empire was based in Des Moines, but had operations and mines throughout southern Iowa.