Have put Bottons, nap size, was concerned with someone waking up with an imprint of the button on a cheek.
Would be concerned with washing on anything with sharp edges, cutting into the fabric. JMO :)

Only embellishments I have put on a quilt are beads, yoyos, fabric flowers and applique.....mainly because I didn't want bits sticking into people when using them. I think if I start doing some art quilts/wallhangings I may branch out, though I've got this "thing" about everything being washable.

I love to embellish quilts: jingle bells on sleigh quilt, costume jewelry on cowgirl hat quilt, fabric feather, beads galore (mostly for eyes). I make polymer buttons specifically for a project - like golfball buttons for a sweatshirt jacket, fish buttons for a tropical shirt, "coal" for the snowmen. My fleece jackets have buttons that match the fabric, just blend the clay colors you need. And, yes, they wash just fine.

Nope, just a traditional quilter. If there is stuff on the quilt, wouldn't it come off in a wash?

On a quilt that is to be used as a wall hanging, I could see using anything that completes the story.
For a traditional quilt that is used on a bed, I don't even use buttons. I like to see the patchwork and the quilting, and I don't want to lie on buttons or beads.

I have embellished (or tried to) some wallhangings with beads, buttons and ribbons, but never put anything on my quilts that would be used on a bed. I am pretty traditional like others have said. Artsy just does not appeal to me.

Same here.....the most I've added is a button or two on applique

Ink and bleach. I use ink to show shadow and painted bleach to show light.

I have a bunch of 'stuff' that I've collected, ribbons, yarns, etc. - but have not done any of that yet.

I also want to incorporate the aluminum shavings that my husband makes when he mills aluminum. Not sure how I would do that though as they're swirlly bits of really sharp metal that would catch on everything. I'll figure something out someday when I have a design in my head that screams for bright shiny swirlly things I guess.

Hot fix crystals, organza overlay, couching thread (or cool yarn instead...if needed), sequins, beads, pearls, and sometimes painting with thread. But in terms of comfort I minimize what I use. Painting with thread can get really uncomfortable with the heaviness of it. But I'll put the yarn or couching thread around my applique with no hesitation. :)

I have couched threads, added buttons, crystals but I love your ideas!