His WW I draft registration card, filed 12 Sep 1918, records John Edgar Davis, age 20, residence Chilhowee, Johnson Co., Missouri, born 21 May 1898, occupation farming, employer John J. Davis, nearest relative Gertrude L. Davis, same address.

It is possible that they are the following couple:

Jackson Co., Missouri marriage records list the marriage on 24 April 1920 of John E. Davis, age 26, and Velma Johnson, age 18, both residents of Jackson Co., Missouri.

I am not convinced, though, because of the age diffrence for John, and the fact that this John was living in Johnson Co. in the 1920 census this John was still living in Johnson Co. There was also a John E. Davis born about 1896 listed in the 1920 and 1930 censuses of Jackson Co., who fits better for both age and location, although in 1930 he was listed as single.

1930 census of Johnson Co., Missouri, Post Oak township, enumerated 25 April, lists on p. 4A as family #89:
Davis, John E., 31, age at first marriage 24, b. Mo Mo Mo, farmer; Velma, wife, 28, age at first marriage 20, b. Ill Ill Ill, Wallace, Marcus A., lodger, 30, single, b. Mo Ky Mo, farm laborer.