Here's a list of books on Traditional Witchcraft and magic. I'm sure there are dozens of others, so feel free to add your suggestions in the comments!
~Practical Reading~
Traditional Witchcraft: A Cornish Book of Ways
- Gemma Gary
A Deed Without A Name: Unearthing the Legacy of Traditional Witchcraft
- Lee Morgan
Treading the Mill: Practical Craft Working in Modern Traditional Witchcraft
- Nigel G. Pearson
Call of the Horned Piper
- Nigel Aldcroft Jackson
The Way of the Shaman
- Michael Harner (Traditional Witchcraft has quite a few shamanistic attributes, making this worth the read)
Mastering Witchcraft: A Practical Guide for Witches, Warlocks and Covens
- Paul Husson (its more Wicca based, but its a classic with some very strong points)
Village Witch
- Cassandra Latham-Jones
Devon Witchcraft and Folk Ways
- Sarah Hewett
Secrets of East Anglian Magic
- Nigel Pennick
A Grimoire for Modern Cunning Folk: A Practical Guide to Witchcraft on the Crooked Path
- Peter Paddon
Crones Book of Charms and Spells/Crones Book of Magical Words*
- Valerie Worth
The Black Toad: West Country Witchcraft and Magic*
- Gemma Gary
*= These are really just spell books with not much else in them. Theyre good, but not if you want to understand deeper the spiritual side of Traditional Witchcraft.
~Historical Reading~
Cunning Folk and Familiar Spirits
- Emma Wilby
Popular Magic: Cunning-folk in English History
- Owen Davies
Witchcraft in Early North America
- Alison Games
The Archaeology of Ritual and Magic
- Ralph Merrifield
The Power of Words: Studies on Charms and Charming in Europe
- James A. Kapalo, Eva Pocs and William Francis Ryan
The Tradition of Household Spirits: Ancestral Lore and Practices
- Claude Lecouteux
Between the Living and the Dead
- Eva Pocs
Ecstasies: Deciphering the Witches Sabbath
- Carlo Ginzburg and Raymond Rosenthal
The Night Battles: Witchcraft & Agrarian Cults in the Sixteenth & Seventeenth Centuries
- Carlo Ginzburg, John Tedeschi and Anne Tedeschi
Witches, Werewolves, and Fairies: Shapeshifters and Astral Doubles in the Middle Ages
- Claude Lecouteux