The stamp is of Howe McCormick, 500 W. Main St., Gainesville, Fla. I've got 169 in my collection now (waiting for delivery of #170 in the next couple of days) and know of 29 others. Posted here is about the clearest of the stamps on any of the cards ...
Started four years ago this month. Never imagained that a 14 to 17 year old could have collected that many and have that many survive 100 years later....