They were fixed in place with a small clip behind the button hole (these clips are NOT SUPPLIED), as they were obviously not washable, and had to be removed before the clothes were sent for laundry and starching.
Each button is just under half an inch across (1.2 cm approx).
I am not an expert, but I would guess they were probably made in the early decades of the 20th century (Edwardian or Art Deco periods).
Fairly good, usable, condition, but these buttons have been used over the years, and are not perfect.
The pictures are still fairly clear, though there is a little spotting round the edges, as shown, and the colours have faded over the course of a century.
I have not attempted to clean them.
I am not sure if the red spot on one of them was originally part of the design (perhaps a red rose?) or later damage.
Two of the shanks are at a slight angle to the buttons.
The third is bent almost flat.
I do not know if it could be straightened without damaging it.
Please see the pictures.