The question edit shows there is something in the box after all:
soft fabric
a mirror
The box lid opens in an unusual direction, presumably because of the mirror, which is in “portrait” orientation.
My guess is this is a jewellery box provided by the hotel so that jewellery may be removed and kept out of harm’s way, and/or from getting lost.
It is much simpler than such boxes usually are, because it only needs to contain jewellery actually being worn, not a whole collection.
And there is only one of them, because (typically) only one person will have significant jewellery to remove at night.
It’s highly likely this box is decorative, my friend has one almost exactly the same that he bought from a department store, keeps small person items in there. A lot of people would use the box for storage instead of leaving smaller items on a surface, especially where they could roll or be knocked off. B&Bs commonly have personal items that the owner has put into the rooms, there doesn’t have to be one for each person.
Credit:stackoverflow.com‘