My interest in archaeology came as a consequence of my interest in textile crafts. Because I wanted to use natural materials, I wanted to know what materials were used (in the region I live in) in the past. The 'past' starting with the first inhabitants.
That question brought me in a museum showing how people lived here in paleolithic, mesolithic, neolithic and later until iron age. Everything known about that subject comes from archaeological finds (artefacts, but also discoloration in ground layers). The archaeologists working for the museum are in contact with other archaeologists (f.e. at Groningen University).
The interest of most archaeologists is: were and how houses/huts were built back then? And then comes: what was their food and how did they get it (hunting and gathering, or some kind of agriculture, or both)? What clothes and other textiles they had comes last. Not because of lack of interest, but because there are so very little finds of textiles. And tools used to make textiles are often hard to recognise as such.
Permaculture is not only about food. Every thing used in daily life is part of it too. And it isn't only about 'growing' (agriculture). Foraging (hunting and gathering) is part of it too. So (i.m.o.) archaeology is important for permaculture.
To know how people did what they did with what they had in their surroundings (land, water, plants, animals, etc.). In modern society a lot of that knowledge is lost ...