Looks like you mistyped Edward's birth year. Should be 1867, not 1877.http://abish.byui.edu/specialCollections/westernStates/weste...
has the marriage as
Edward O. Sanders + Clara B. Bell; 13 Aug 1905; Union, OR
1920 census shows Edward as a widower with the three children. His parents shown as born TN and MO. They've moved to Smith Mountain in Wallowa County.
I haven't found Edward in 1930.
1940 census shows Edward, age 73, living in Polk County with Le Bell and Ermal O.
1900 census shows an Edward Sanders, born Apr 1867 Illinois, a single border with Josh and Kittie Gray in Hilgard, Union, Oregon. Parents born TN and MO. Working as a "Timber Laborer". No apparent relationship to the Grays.
And the payoff...
Saunders, J. E. W M 43 Head TN VA TN
Frances O. W F 38 Wife MO NY CT
Elvin L. W M 19 Son IL TN MO
George T. W M 15 Son IL TN MO
Edward O. W M 12 Son IL TN MO
R. R. W M 10 Son MO TN MO
Clarence C. W M 8 Son MO TN MO
Leadelia W F 1 Dau CO TN MO
I haven't yet been able to trace J.E. and Frances any further. Looks like they would have married about 1860, possibly in Illinois. They started migrating west about 1869, first to Missouri, then Colorado, finally Oregon. I've seen records indicating that Elvin was in Oregon around 1891. Unclear if the parents made it there from Colorado.