You didn't note a timeframe but it appears from this census data that the names of the children match. Different middle initial for Willie? Could be a typo or transcription error. By the age of son Daniel, he may have had a different mom.
Try the free search tool at https://familysearch.org/ and plug in the children's names/est dob etc. to see if you can find more details.
Please note that each familysearch page has a citation at the bottom to be used in your references.
United States Census, 1940 Militia District 351, Tattnall, GA
head W D Mills M 53 GA
wife Ellen Mills F 35 SC
son Daniel Mills M 19 GA
dau Ella Mills F 15 GA
son Elton Mills M 12 GA
son Bennie Mills M 9 GA
son Louis Mills M 2 GA
Georgia, Marriages (possible match – but needs confirmation)
groom's name: Willie D. Mills
bride's name: Mary E. Powell
marriage date: 28 Aug 1924
indexing project (batch) number: M39619-1