Hmm. After reading more. I was looking at wrong button on the site. Mine does say
"Maryland button, state seal eagle over a coat of arms with a fisherman and farmer, officer staff, Horstmann Bros & Co Phil, (15mm)
Button depicts state seal of Maryland, a shield with a fisherman, farmer, and eagle. Backmark: HORSTMANN BROS. & CO. / (dot) PHIL. (dot) " dm small letters inner ring of dots, small size only, backmark is likely post war, (HorstmannB16, small). Three part officer staff button, coat size.
Ref: Albert MD11, not listed, TiceMD200, not listed. Manufactured after the Civil War."
I was hoping I has my first Civil War relic.