I can't tell you who is buried in the lot. I did look through all of the cemeteries in Kingfisher County that are online but didn't find any Walford's.
There are a couple of people you can contact to find out more info about that lot. Surely the local funeral homes should know if someone is buried there without a stone or if it's available for purchase. I tried to look up the cemetery itself but didn't find any organization that claimed it.
Funeral homes are at www.okcemeteries.net/kingfisher/funeral.html. You might have to scroll down to the bottom and look for Funeral Homes of Kingfisher County.
A fellow also indexed Grimes Cemetery, www.okcemeteries.net/kingfisher/grimes/grimes.htm and he might be able to provide more info too.
Maybe you already know this but Oklahoma doesn't publish their vital record dates. To find death dates you need to go through cemetery indexes, look for obituaries orcontact funeral homes.
You can order a copy of a death certificate after 1907 but you have to tell the Oklahoma Dept Health, www.ok.gov/health/Birth_and_Death_Certificates/ when and where the persond died.
I did find the following: Mrs. George Walford, died March 18, 1931, 63 years Source: 1931 Death Records from Kingfisher Times, www.okcemeteries.net/kingfisher/kingfisher.htm.
I thought it odd that if George's brother bought the plot/lot, I didn't find more Walford's buried in the County. However, in 1930 William Albertus Walford was living in Sparta, Crawford, Pennsylvania. He died there 8 Sept 1930, shotgun wound. Source: Tangled Roots family tree, ancestry.com. Most larger libraries provide free access to Ancestry with a local library card. Successful Searching!