The BLM land grants that identify this property are here:
https://glorecords.blm.gov/details/patent/default.aspx?accession=MO3180__.450&docClass=STA&sid=ywml0bt3.iat
This is at the junction of Grassland School Rd and Audrain Co Rd 924 3 miles SE of Centralia and just South of the massacre site.
The farm actually straddles the Boone /Audrain County line. Time to dig into the plat maps and Google Earth!