John Tobey has a marker about a meter from this wonderful, wonderful concrete cross with embedded marbles at Mt. Olivet Cemetery in Washington, D.C. There is nothing else nearby, so I assume the cross was made for his grave.
I infer that the plaque’s single date is meant to be read as a birth and death day, though nothing substantial backs up my guess. The marbles motif certainly works for a child, and as a homespun method of adding color to a concrete cross we might not press it too hard in thinking about the age of the dead child commemorated.