Central Railroad of New Jersey Button, with "Scovill. Mfg. Co./Waterbury." backmark.  This rail line was established in 1849.  They operated more than 63 miles of line by 1852.  As the eastward extension was not opened until 1864, the button may be just Post Civil War.  The foregoing information is from Volume Number one of Don VanCourt's, Transportation Uniform Buttons. It is a nice early U. S. Rail Road button.  I have kept one for my personal collection and was delighted to pick this up to offer.