hello Abgkyle , its a very interesting button however its not listed in any of the military button books that i have . the eagle motifs the military uses are almost exclusively full bodied birds with other items military related with them , none use just the eagles head and in a way like your button shows. the button's two piece construction alone suggests it is a late 1800 to early 1900 style . i'm guessing maybe off of a hunting jacket , blazer or school (possibly military school or academy) of somekind . sorry i coundn't be more help .
Dan