I am curious if anyone can help me with this Horstmann Philada coat button. Shiny brass, nice patina. It measures 2cm. I have no idea how old it is. Any info would be appreciated. Thanks!
Your button is a US Army "general service" button for Enlisted-men's uniforms. The specific version you've got, on which the eagle's head somewhat resembles a chicken's head, with a raised shield on its chest, was in service from 1875 to 1902 (when it was replaced by the "Great Seal" button).
Wow! Thanks, this was in my grandfather's collection. Any idea of what these are actually worth? I saw some listings on ebay for around $25.00. My great grandfather served in the Spanish American war, could this be a button from his uniform?
Because you asked... based on its particular version of Horstmann Co. backmark ("HORSTMANN * PHILADa"), your button dates from 1893 to no later than 1902 (when production of that button-emblem ended). So yes, it could have come from your great-grandfathers Spanish-American war (1898) uniform.
Edit: I forgot to answer your question, "Any idea what these [buttons] are worth?" It is unwise to rely on Ebay for dollar-values of relics. Anybody can buy these chicken-head eagle buttons for $2-to-$3 at various Militaria shows and gun-shows. That's because they are far more common than (let's say for example) your Kentucky State Seal button from the same time-period. There were literally millions of Enlisted-men (privates, corporals, sergeants) in the US army between the 1870s and 1902.