I say, why not?
Buttons can make for some interesting additions to a quilt top.
Two considerations ....
.... is it for a child? the buttons would need to be secure, so a child could not get them off, and swallow. Or perhaps be scratched, if sharp edges.
.... quilting! Depending on how you will be quilting, and the placement of the buttons, you may be best to leave them off, until after all assembly and quilting are completed.