The kirtle is hand sewn in hand woven linen twill. There's two layers of it in the bodice and a single layer in the skirt.
Though they probably weren't that common compared to woollen ones there is documentation for linen kirtles in the 15th century: for example a swedish document from 1507 mentions a linen kirtle and then there's the remnants of two linen kirtles (one a woman's and one a child's) of northern german origin in the national museum in Helsinki, Finland (Pylkkänen, Riitta: 'Überreste von Leinenunterzeug aus der zweiten Hälfte des XV. Jahrhunderts in Finnlands Nationalmuseum' in Waffen und Kostümkunde 2, München &Berlin 1960. They have been interpreted as smocks, but I think it is just as likely that they are kirtles.
I would never use linen for the top layer, but these kirtles are more like a kind of underwear that you can wear in public if you're a peasant or worker, so I decided that I was a working woman during the day of this particular event.
The headcloth is also hand woven linen, while my socks and apron are from wool and the gefrens from silk.
A gefrens is a head decoration often found in paintings and drawings depicting german women from the 15th and early 16th century. It's basically a cord with a fringe that hangs down over the neck. I made it by inserting extra pieces of silk yarn with the weft when tablet weaving to create a fringe. I't far from perfect, but I made it in a few hours and thus I could wear it at it at an SCA event the next day. I would have liked it to be a brighter red and somewhat thicker, but at least the silk yarn is dyed with madder (by me and my friend Ragnhild) and it's nice as a first try.
And now I wouldn't fit into that kirtle, so I can't take new photos.