Two more ....

Cutwork button - half of the covering fabric is cut away
and replaced by another fabric - of course
it has to be "buttonholed" at first -
and then embellished with French knots, bullions and two chain stitches, two,
more cannot  be placed on this 2,9 cm large button

A little round hole cut into the fabric
some embellishments, tiny, tiny.

Buttons can look like that
and the two rolls are called toggles