My long silence does not indicate inactivity—rather it is the result of non-productive activity.  Would you believe I have searched the occupants of fifty or more cemeteries in DeSoto County, Mississippi that are listed online?  Then I contacted the County Historical Society to ask for assistance in locating Stewart's Store, the precinct (or parish) in which the 1880 listing for Adam Sherman also includes 18 year-old Samuel, his brother, as well as Adam's son Samuel, age 4.  The census also lists his sister Ella, so I am trying to find out more about her, and the man from that vicinity that she married, William L. Manly.

But the response from the history group was that they did not have information about that location, but would continue to investigate.  One bright note is that when I typed in Stewart's Store on one genealogy site, a map popped up with an arrow indicating a spot just north of IH 69 and just west of US Hwy 51 N.  I quickly emailed my contact, but have not heard back whether that helped find that area. 

Since Adam (or Adsn [legible penmanship did not seem to be one of the requirements for 19th century census-takers]) was listed in both 1870 and 1880 US Censuses, it seemed possible that the location of their farm (his listed occupation) might be a clue.  Perhaps it could have been where Samuel W. was born, since it is just south of Memphis.

Anyway, that is the assumption that I am following at this time.