There's no such thing as a
stock background in period photography; suppliers of photographic materials like chemicals, brass mats ( made by Scovill who also made other stamped brass items like buttons ), cases, etc., etc. didn't make or provide them. In big cities backdrops were usually painted on canvas by theatrical scenery painters; in small towns they were home-made, often by the photographer himself. Careful examination of backdrops often provide clues as to
where a photo was taken and
by whom. ( That's why noman's asking the question. ) In an example from my own collection, when I posted this ambrotype on another forum a sharp-eyed reader recognized it as containing the famous ( among collectors )
Gabled House and Pine Tree backdrop known to have appeared only in photos of North Carolina Confederate officers!