I found another diagonal DPW stamp! A pair, this time, on facing blocks. This is on the west side of Shepard just south of Marcus, in front of the house on the corner.

The year is extremely hard to read. I can definitely make out that the last digit is a 1. The decade digit is a lot murkier. Feeling it I thought I made out 2, thus 1921, but I can’t be at all sure. 1931 is another possibility.