It might have been either a Scholastic or Weekly Reader children’s book, from either the late ‘60s or early ‘70s; but I might have just stumbled onto it in a random store.
I think it was a small, thin, hardcover book with a primarily medium-blue cover.
I think it had a relatively simple title, like Magic Spells and Potions, or something like that, but I can’t remember.
What I do remember clearly is my favorite spell in the book, which involved going into the forest and finding fern “seeds” with which to acquire the power of invisibility.
This wouldn’t be How to Make Magic by Finmark and Wickers, would it?
I’ve been trying to remember this book myself, or at least I *think* it’s this book.
Is this the one? The Witch’s Catalog (by Norman Bridwell)
https://the-haunted-closet.blogspot.com/2009/02/witchs-catalog-norman-bridwell-1976.html
(more pages can be seen here: http://www.ladybridget.com/p/catalog.html)