I learned strawplaiting from Shelley Osborne, then of Walpole, NH, and from Marilyn Stearns of Springfield, Vermont, back in the 1970's. Marilyn had learned from Valerie Eastwood and Joan Hocking in Sussex, England, so my tradition is definitely by oral transmission - the folk process! The custom is many centuries old, almost a pagan prayer which thanks the earth for it's abundance. My rye & oat straw is all locally grown; the wheat is grown on a family farm in North Dakota where the long days of sun ripen the straw to the clear golden color necessary for ornamental work.
(I have experimented repeatedly with growing my own ornamental wheat here and been very disappointed by low quality of stem & head color.
The plaited birchbark work I learned as a tradition and skill from Karin Lundholm, a teacher for the state-sponsored Hemslojden Association in Dalarna, Sweden. I first worked with her little handbook (all in Swedish - Ja!!), then was able to take a week-long class with her, communicating through a translator. All my birchbark is harvested responsibly and locally with Peter Rhoades, a forester, as part of his ongoing woodlot management. Nothing is wasted by our harvest. As with the straw tradition, bark plaiting has been a rural tradition in Scandinavia for centuries. People even paid their taxes in birchbark! It was used for roofing, for farm containers, for shoes, and even - sadly - in times of famine - for food.
I make every ornament myself completely by hand at our kitchen table in our cottage home in Langdon, NH.