I have some blocks I purchased in Atlanta a few years ago that fit into this category of "improvised" quilts. If I were to define the blocks, I would say they are Log Cabin blocks. But no two are alike. The size of the strips are all different, and they aren't perfect squares or rectangles. A few of the blocks have the same fabric in the center, but strips around the center appear to be whatever was at hand. Some of the "strips" are actually hems -- hems cut off shirt sleeves, perhaps, and still turned under and sewn.
It is hard to tell how old the blocks are and what era the fabrics came from. An expert in textile history could tell, but I can't. I don't see feed sacks but there are wonderfully bright colors and prints. I'm sure they all came from clothing, so the best resource for dating them may be catalogs and fashion magazines.
After listening to Deb and seeing her quilts, I'm inspired to go ahead and put these blocks together, perhaps with a plain muslin sashing so as not to distract from the blocks and the fabrics. And I want to cut the sashing with scissors, not a rotary cutter, just as the original piecer would have done. I wish I knew who made them, and what they intended to do with the blocks. I hope wherever that person is, they will be happy with the finished quilt.