I agree with fyrffytr1. I believe we are seeing "Black Finish" camouflage on your US Army general-service "Great Seal" button, which dates it to being from World War One to 1923. Most probably, it is wartime-made because there were so many leftovers from the "downsizing" of the US army after the war that few if any new ones needed to be made. Whoever put that chart of Scovill dates onto the internet should correct it or take it down. "Scovill Mfg. Co. Waterbury" appears on Scovill button backmarks for 112 years, (1850 to 1962), when Scovill stopped making buttons. The backmark's punctuation, with stars or dots or "florals" or without, lettering size, and lettering "font" (serified or plain-block letters), tell the time-period. If you want to see nearly all of the known variations of Scovill backmarks, the best book on button backmark dating, "American Military Button Makers And Dealers; Their Backmarks & Dates, has dozens of photos showing the Scovill backmark variations from specific time-periods.