I was looking in an Elkhart County History book at the library the other day, and read about your ggrandfather,Jesse Rush.
[Although Dr. Havilah Beardsley is given just credit for founding Elkhart, the portion of the city north of the St. Joseph River embraces the old Town of Pulaski, or rather the little settlement which centered in the postoffice by that name, and which lifted itself modestly above Elkhart Prairie two or three years before the doctor platted Elkhart.References has been made to Joseph Noffsinger, who squatted on the north shore at the mouth of the Christiana, as early as 1821, and to the coming of the Rev. Isaac McCoy to that locality a few years afterward.In 1827 Jesse Rush and family settled there permanently and there it was, on may 16,1828, that Mrs. Rush added the first natives to the population of the county by bringing forth twins, one of whom, Isaiah Rush, lived to be a venerable citizen of Elkhart.]
I found this in the book—A Standard History of Elkhart County, IN Vol.#1 Under the Editorial Supervision of Abraham E. Weaver/Printed by The American Historical Society Chicago and NY1916. I hope this helps a little.If you haven't already found out where they are buried at, I will try and find out for you.