My Grishams passed from Virginia to Tennessee to Boonville, Mississippi to the Wichita Falls area. I have tracked down census records for most of my ancestors on this line. If you think it might help you find your Denton Grishams, I'd be happy to let you browse these records on my tree. If you'd like to do that, please send your e-mail address to me at vaughngrisham at gmail.com and I'll send you an invite.
When I was searching for the Wichita Falls records for the family of my paternal 2nd great grandfather, William Jackson Grisham and his wife Lillie Woody, I did stumble across some other North Texas Grishams in the Wichita Falls Newspaper archives. In the February 24, 1915 edition of the Wichita Falls Daily Times, there is an article about the acquittal of T. M. Grisham of Electra, Texas on murder charges. I haven't figured out who this guy was; he wasn't an immediate relative of William Jackson Grisham.