Looking at the 1840 US Federal Census for Dyer Co TN and studying those who were enumerated around my 2nd Great Grandfather Wm C Cook. Most of those that remained in Dyer Co are enumerated in 1850 Federal Census in District 9. I looked at maps for the years before and after 1840 and I believe that they would have been in the Eastern section of District 4 which was District 9 by 1850.
The most interesting find so far is the household enumerated immediately before Wm C. Cook. That head of household is R. A. H. McCorkle. Robert Andrew Hope McCorkle went to Nauvoo, IL in 1844. He was interested in learning about the Mormon religion and had questions for Joseph Smith. He didn't get to speak to Smith but did write to him and that correspondence was saved and is interesting reading. It's a great insight into one of Wm C Cook's neighbors. You can find more info about this letter at the link below. This family was also in the Rutherford Co TN area prior to coming to Dyer Co. TN. Prior to coming to TN they were in Rowan & Iredell Co. NC area. Also Gillespie and Brandon ancestry in the McCorkle family.