Thanks to both of you. I have found an obit for Leon in the 21 Jul 1957 Wyoming State Tribune. And I had found one for Anna in the 15 Nov 1921 Le Mars (Iowa) Weekly Sentinel.
I'm fairly sure that Edith (Jordan) Davis died on 8 Jun 1971, probably in Cheyenne, and haven't found an obit for her, although I haven't really exhausted all avenues for her yet.
Thanks again for your help.