Another received Monday but not yet scanned, so I'm sharing the seller's images. (I didn't pay $35. :P )

From The Massachusetts Anti-Double-Taxation League addressed to Peter C. Brooks, Esq, W. Medford, Mass.
Postmarked with flag cancel 11 PM, August 31, 1899, in Boston.
Received 7 AM, September 1, 1899, in West Medford, Mass. Stamped "Forwarded from West Medford, Mass."
Second postmark 8 AM, September 1, 1899, in West Medford, Mass.
Received 9AM, September 11(?), 1899, in Wareham, Mass.