I'm having difficulty tracking down Flora, but I've created profiles for Millard E. Allen and his wife Effie Key here on WikiTree to help you get a start on the reserach:
https://www.wikitree.com/wiki/Key-3390
https://www.wikitree.com/wiki/Allen-35242
I have a marriage record for Millard and Effie. However, he may have married again, to a Emma Younce, who shows up with him in the 1930 Census of the same county.