Hi...

Not sure where Jane Shaw Henegan is buried [is that her, age 78 and widowed in an 1880 Knox County Census?]

MIGHT (I stress 'might' here) have found a possible marriage record for her and William....there's a Scottish marriage record for a William Henigan marrying a Jane Shaw in Old Monkland, Lanark, Scotland, on July 17, 1825. MAYBE that's them?..?..?..?

IF that's your Jane Henegan in that 1880 Knox Census, she probably is buried in Knox County somewhere....and may be in an unmarked grave. [I myself have a few ancestors that died in the late 1880's in that area - no clue where they are either.] IF that's not your Jane in that 1880 Knox Census, any chance she died in Iowa too when Wm was there?

Good luck in your search,

Kat