The jacket is old like a decade or so or even more.
I had plan to purchased some buttons, but was curious about what the original buttons were made of and how it could become like this. I am thinking that the original buttons were some sort of wood. Plastic buttons don't usually chip around the edge, but usually start breaking in half.
The reason I ask about the material was to figure out what material to replace it with. I think the usual choices are: plastic, horn, mother of pearl, wood/nut, metal, and leather. Leather and metal seems wrong for this type of jacket. I think horn is probably the most durable out of the group.