I have read a great many books purporting to be of Witchcraft, and many do have a good deal of the history of the craft.Janet Farrar wrote very well about what the ancient witches must have been like.
But, and it is a big "but", all the books I have read had some form of the Occult; all had references to Gods or Goddesses, things of "mystery". None gave very much information on the actual "craft".
And the reason soon becomes very clear; the ancient witches wrote nothing! The knowledge was "handed" down by word of mouth.I was taught that way; and why my teacher told me to "write everything down in your notebooks."
The nearest thing you can get to reading of my kind of natural witchcraft, is to read books on the Natural world. How Nature works (mainly by accident!) and how the Universe works. The real meaning of "resurrection". The study of plants and fungi. (Especially fungi; without which there would be no trees!)
At school I was told that the biggest animal was the blue whale, the biggest "organism" was the California Redwood.
My witch teacher told me the truth. The largest organism on Earth is a Fungus!
To me, there is nothing supernatural about witchcraft.It is all right there, before your eyes mostly, but sometimes hidden!