This daguerreotype portrait photo was found on the body of a Union soldier who died in a 2nd Corps field hospital during the Siege of Petersburg in 1864/1865. The note also mentions that the soldier might have served with the 4th New York Artillery. The note inside the case was added probably by the person who found it. It doesn't seem like the location of the burial of the dead soldier war recorded.
Source.
Similar story of photos found on battlefields from a few years ago.