Hi Janet, I've look through two on-line death record indexes but neither one went back to 1874. Oregon didn't require death information on the State level until 1903.
However, you can find a public record and library look-up volunteer at Random Acts Genealogical Kindness. Go to raogk.org, read guidelines, choose Oregon, choose Marion Co. and choose one volunteer who does public record and library lookups.
The volunteer will want to find the exact death date first and then look for his obituary.
I also found the Harper Family Tree on Ancestry which contains information about Layfayette. Successful Searching!