Eileen: It used to be possible to find buttons with a metal loop on
the back which fit through a (bound) hole in the fabric, and had a
small, springy clip which was pushed onto the loop (under the
fabric) and which held it in place. It could easily pulled out and
the button removed when necessary.
^^^^ The top of the clip looked like this, the bottom was a
straight line (can’t get my computer to put them both together)
I don’t know whether anyone makes these anymore, but I imagine a
similar thing could be made out of a springy wire.
I believe I still have a few around, so if you would like a picture
e-mail me directly.