Their death certs (post ~1918) should have asked parents' names ...
And if you like PInnell, here is a researcher from the county page:
Surnames: MERRIMAN HUDGINS PINNELL BROWN Submitter: Beau Hudgins (firstname.lastname@example.org) Date: 01 Oct 1998
Trying to find out what happened to Franklin L. MERRIMAN. He was born 1858 Illinois. His parents were Richard D. MERRIMAN and JEllen BONHAM. Franklin MERRIMAN m. Oct 2, 1892 Eldorado, Ill. to Eliza B. PINNELL. She was the dgt. of William A. PINNELL and Minerva BROWN. Franklin and Eliza had one son Ernie MERRIMAN b. 1894 Eldorado, Ill. and then apparently Eliza died of the flu and Franklin left his small son to be raised by Rev. Joe Lane HUDGINS. Franklin just disappeared and when his son ( Ernie) grew older he just started using the surname of HUDGINS instead of MERRIMAN.