The mother/daughter dresses were likely made from feed bags. In the 1930s - 1950s feed bag companies used fancy printed cloth that farm women could make into clothing for the family.

An unusually spectacular example is here:

http://americanhistory.si.edu/collections/search/object/nmah_1105750

My great grandfather was in management at the Chase Bag Company in Milwaukee. I well remember wearing shirts made of this cloth which my mother's family called "pretty prints."

I notice that the woman and the little girl on the right are wearing dresses made from the same print material. I suspect that the mother made them, from fabric and patterns bought at the local sewing shop.