I use at least one button, and often many more than one, on every quilt I make. I did an applique carousel horse once and lost one of the tails so I did that one tail all in brown buttons. I put that tail up near the top and my daughter (then six) would rub her fingers across them until she fell asleep. She's eighteen now and still has that quilt though she has put it away now for her someday daughter.
On a seed packet quilt I placed tiny lady bug buttons in various places on the plant pictures.
On my daughters wedding quilt, instead of a quilt tag, I embroidered the information onto the backing fabric, white on white, and placed a small pearl button under the embroidery work so it would be easier to find the corner that's embroidered.
Well, you get my meaning by now...I would keep them, cherish them and use them!