Depends on the age of the child. For those 3 & under, I personally would never ever do real buttons. I've made larger "buttons" out of felt & ordered iron-on decals for one adorable baby quilt pattern I used that called for 42 1/4" buttons. The iron on decals came with the center holes punched out & everything. They were super realistic!
Over the age of 3 -- and assuming younger children or certain pets wouldn't also have access to the quilt -- it would depend on the age & maturity level of the child.