You may be particularly interested in this table of all of the graves I could find [PDF, 42 Kb], when I was asked about women wearing only a linen underdress with an apron dress over the top, and what material the dress loop-straps were made of. The majority of the graves appear to have evidence pointing towards women having linen straps, even when their apron dress is made of wool. It is tempting to suggest this was intentional, and the linen straps perhaps blended in with the linen dress worn underneath?

2022 Update: a much better place to look for information is Hilde Thunem's excellent website.