Coffin nails, square nails. Vintage nails for use in your magical workings.
In Hoodoo, coffin nails are used for malicious workings. You can order a set of 9 charged with and shipped in guffa/goofer dust. Crooked nails are strongest for witch bottles or war water. You may also purchase sets of 6 or 9 that are kept in graveyard dirt. (These are limited in number and may add processing time.)
You can also use coffin nails for protection spells by binding them into a cross shape, or you can use them to scribe into wax. You can purchase a set of 3 charged with neutral earth for this purpose. This is the least expensive option. (You may also use nails charged with graveyard dirt for powerful protection spells.)