Sewred-
Well then those navy fabrics are indigoes, and they probably date to the 1800's. Do you see the fabric at the top of the first photo which looks like a gradated dark to light red, paired in the 4 patch with a solid salmon (?) color? That looks to me like an "ombre", and if so, it dates to the 1800's. Computer monitors sometimes show colors inaccurately, so it's hard to be sure, but some of the solid pinks you have may be "bubble gum" pinks from the 1930's. Even then some quilters had stashes and quilts were often done with fabrics ranging over quite a number of years. Sometimes that happened when one family member started the quilt, then a daughter/niece or someone else finished it, many years later. As for the backing, you could use a reproduction fabric from around the turn of the century, or you could just use a good quality muslin. Muslin has been used for quilts for forever, so that would be true to the time frame, too.
I have a 1930's Trip Around the World quilt top I bought on eBay which I am enlarging with reproduction fabrics. On the back I will include a legend stating where the original fabrics are and where the reproductions begin.
If you are interested in learning more about vintage fabrics, the first book I would recommend is Eileen Trestain's Fabric Dating. There are two of them: one with photos and descriptions of really old fabrics, and in the second book the fabrics are more recent. Your fabrics would fall into the first book of hers. Have fun on your new journey! Let me know if I can be of any further help.