If your blocks were done with unbleached muslin, I would take some of the smaller ones to a qult shop or fabric store and try to match the color and then add strips onto the smaller blocks. Muslin especially unbleached CAN be hard to match. So someone else's suggestion of tea dying the newer stuff might be an option if all else fails.
But you are so blessed to have that! My mother sewed for us (garments) and so did my grandmother, but my sister and I are the 1st generation of quilters in the family that we know of.