Could be anything with the initials BBB. Baptist Boys Brigade, for example, had their own belt plate with the initials BBB. They apparently were the most popular youth association in the late 1800's. There was also a Boston Brigade Band.
There were tons of these wreaths left over from the war and they were repurposed by Bannerman and Stokes Kirk. They would make up anything you wanted for your organization, whether it was SUV, SCV, UCV or GAR.