Wattle and Daub
Wattle and daub is one of my favourite natural building techniques because it's relatively easy to do it single handedly. Normally, a post and beam structure would be interwoven with long fresh hazel or willow sticks. After that the whole structure is covered in earthen plaster. There are many variations on the wattle and daub theme, however. Have a read of these articles to see what you can do with wattle and daub.