All of the colors in the curtains would work and if you want to add green, pick a multi-color print with green in it. OR you could go with all neutrals although I am personally not a fan of quilts without some pop of color.
I totally agree with the Quatrefoil pattern comment because it has become one of my favorite patterns. You can easily use a multi-colored print for the center petals and use neutrals for the center and background as well as sashing and cornerstones.