Charles Godfrey Leland was a folklorist who befriended magical practitioners and then shared what he had learned about their practices. A classic.
Christmas In Ritual and Tradition, Christian and Pagan by Clement A. Miles (EPUB)
An interesting book from 1912 exploring the history of the Christian holiday of Christmas, particularly its Pagan roots. This EPUB edition obtained from Project Gutenberg. Other electronic formats of this book are available at https://www.gutenberg.org/ebooks/19098
Plant Lore, Legends, and Lyrics by Richard Folkard (EPUB)
Folklore about plants, including information on magical uses. This EPUB obtained from Project Gutenberg. Other electronic formats are available for download at https://www.gutenberg.org/ebooks/44638
The Golden Bough: A Study of Magic and Religion by James George Frazer (EPUB)
The classic text on mythology, folklore, religion, and magic first published around 1890 in multiple volumes — it’s actually a whole encyclopedia set on the topic. This document is a popular single-volume edition.
Different electronic formats of this ebook are available for download from Project Gutenberg at https://www.gutenberg.org/ebooks/3623