Old WWI soldier grave site photograph

I'm not sure what connection this photograph has to the original owners of the estate where I found it, so it may be possible one of the Privates was a relative. Private Nels Klep is registered as being from the city of Bagley, in Clearwater County, Minnesota served in Company A 34th Engineers and Died of Disease. Private George C. Guardenier is registered as being from the city of Hoboken, in Hudson County, New Jersey and served in the 313th Quartermaster Supply Company and also died of disease. The dates of death are not recorded on the WarMemorial.US website but I enlarged the images on a Merlin Enhanced Vision viewer for clarification.
I am not an expert on military and war history, so please feel free to add or change any of my research. I enjoyed investigating these servicemen and think someone should add the missing dates of death to the history site.

Sources:
Private Nels Klep - http://warmemorial.us/mediawiki3/index.php?title=NELS_KLEPP_-_MN_(Bagley)_WWI

Private George C. Guardenier - http://warmemorial.us/mediawiki3/index.php?title=GEORGE_C._GUARDENIER_-_NJ_(Hoboken)_WWI