Hello again, Goldenponder:
I finally had a chance to check my books—wish I had done so for you sooner. I found your button maker. Evidently, indeed, a post-American Civil War maker, but a nice button find nonetheless. From “American Military Button Makers and Dealers; Their Backmarks & Dates,” by McGuinn and Bazelon, published by the same, Fredericksburg, VA, 2001 (Enlarged Edition), p. 88:
“New York Clothing House, Baltimore, MD. Retail clothiers at 102 E. Balto. St. from 1892-1921 but Rosenfeld Bros. began in c. 1865 per CD listings. They advertised military uniforms from at least 1908-12.
“N.Y. Clothing House/Balt’o, Md” (MD-18; FD-57A; MD-12)
“N.Y. Clothing House/Bald(sic) Md*” (MD-13)
“N.Y. Clothing House/Balt, Md.” (MD-13)