My research showed that red or yellow was generally used, representing the "home fires" ...
If making the quilt for a family, and/or representing family, sometimes black was used to indicate that someone had died, or that "branch" of the family tree was "lost"...
Black was also used for URR quilts, however, there is a lot of "myth" stories out there regarding URR quilts. Sometimes it's difficult to weed out what is true and what isn't when you are discussing those quilts ...
HTH