If you happen to have an image that can be posted of the button in question, it would much better serve the inquiry, as well as spawn more responses. Unmarked buttons of the era both war-time and post war are not unusual. A host of various contract makers and smaller manufacturing operations didn't bother to mark their buttons... The respective design style and stamping feature characteristics can many times aid in determining the general age or time frame of a button. Since they commonly evolved over time as well as different makers may have slightly different patterns in use. Assembly methods, and materials used can also sometimes be used to make a determination. Buttons of this era were also replicated in mass for post war veterans groups... military schools-academies... post war state militias... and still are for modern day reenactors... so such "post-war" title on a button could imply anything from 1870 to 1970's...
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