I also found this unusual box that was filled with sewing items.
opens to lay flat
side view open
Here's what was inside, a needle case, marking wheel, button hook (?), bobbin.
A brief internet search uncovered that this box was indeed a sewing related box, however it is called a puzzle box and originally held Singer sewing machine attachments. I found some photos that showed the same box with all the machine attachments in place. My box lacks the metal mounting brackets (but the holes remain) that held the parts in place.