It is a 1-piece brass civilian-usage button. Due to the "floral-style" emblem on its front, relic-diggers typically call it a flower-button. Definitely not an actual Military-Issue button, although some "needy" Confederates are known to have used a flower-button (or a plain-front brass 1-piece flatbutton) when they couldn't get a replacements for lost Military buttons. Your button's backmark saying B&B means it was manufactured by Benedict & Burnham, located in Waterbury CT. The firm was in business under that name only from 1834 to 1843... so your button was made during that time-period. The name was changed in 1843 by adding "Manufacturing Company" to the prior name, so buttons made by that firm from late-1843 to 1849 include the "Mfg. Co." in the button's backmark. Yours lacks the "Mfg. Co." so it is from 1834-43. In 1849 the firm became the "Waterbury Button Company" -- which manufactured millions of civil war Military buttons. It is still in business today, manufacturing both Military and Civilian-usage buttons.
Regards,
Pete
