Priced $9.80. Antique Military Navy Button Scovill Mfg Co. Anchor Left Facing Eagle 13 Stars - Civil War Era Measurements: approx. 1/2" diameter... Condition: as found, please see pics... Please email for details and more pics as needed to make an informe...
Certain specific details in the emblem on your find prove it is an "Imitation-Navy" Civilian-usage button made for use on fashionable coats & jackets.
Notice that the rope border does not pass through the ring on the anchor. ALL actual Military-issue US Navy buttons from about 1852 to the present show the rope border passing through the anchor's ring. See the photo below which shows a genuine civil war era US Navy button.
Also, the Fashion Faux-Navy buttons typically show the eagle's wings having "rounded" tops. But the wings always have "pointy" tops on actual 1852-Present US Navy buttons. Again, compare the shape of yours with the actual US Navy button in the photo below.
The Fashion imitation-navy buttons' eagle emblem typically shows what is called "weak detail." On actual US Navy buttons, the details are all very sharp. For example, even the individual feathers on the eagle are crisply defined... look closely and you can see the vane-lines in some feathers.
Lastly... actual US Navy Uniform buttons NEVER have an iron/steel back. Your photos seem to show some bits of brown rust encrustation around your button's edges. The iron/steel back on the Fashion buttons typically rusts out after a couple of decades in the ground.