You might want to post to the Yamhill County Genforum board and see if anyone will check the IOOF Cemetery in Dayton, Oregon for you, for more information on Alvin G. SHEPARD's death. Maybe the local newspaper would have published a funeral notice or obituary for him. The only thing at the Find A Grave website regarding him shows a birth year of 1861 and death year of 1939. No month and day were listed. I couldn't find him listed on Ancestry's death index for Oregon. The cemetery should have a record of the funeral home, and should also have a date regarding when he was buried. If he died outside of Oregon, there should also be a note as to where he died. The newspaper should mention survivors, and if your Cleo did marry Alvin 24 May 1935, she should be listed as a survivor if she didn't die before him. There should also be something in the local newspaper when Cleo and Alvin married in 1935.
Do you have any information on Oma Mae AGER's daughter, Bernadine Corleone McCord, listed in Oma's obituary as living in Charleston [Coos County], Oregon in Sept. 1958?