I think I can see "tone" in a quilt, and color (obvious if you are not color blind), but I don't get what the "value" is. I'm not implying I'm particularly good at choosing colors together, but I can see clearly what the color is. But what's value? Depth? size of the prints? I don't really get it.
Value is how light or dark your fabric is. The link below might be helpful.
http://quiltblocklibrary.com/quiltblocks-color3.html