Since I was a child, I’ve had a bit of an obsession with rocks. I think this mainly had to do with growing up in an area with some spectacular rocks to collect.
My favorites were what we called sparkly rocks which you mainly find around creeks. Most of mine I found around Viburnum, Missouri, an area with large lead deposits.
But in addition to sparkly rocks and fossils (which I also loved), I always kept my eye out (and still do) for witch stones.
Witch stones, also known as fairy stones and hagstones, are rocks with a naturally occurring hole in them. As you can probably guess, the best hunting grounds for these rocks is also near streams since water is what washes away parts of the stone to form the hole.
Holly Black made witch stones (she called them fairy stones) somewhat famous with her use of them in the Spiderwick Chronicles. In her stories you used the stones to see the fairy world, but they are probably better known as a way to ward off evil. 
According to this article, people used to hang them over doorways (especially of stables) or wore them around their necks and some even used them as a spout through which the poured milk to keep it from curdling.
I’m not sure as a child anyone ever told me what they were supposed to do, but I’ve always thought of them as witch stones and known they carry with them some kind of magic that I want to possess. 
Any of you own witch stones? How do you use them?
I love rocks too. Didn’t think anyone else did :-) Haven’t ever heard of these stones before.
I do not have any witch stones but I have many obsidian (volcanic glass) pieces. They come in many colors: Black, green, purple, amber (sometimes called root beer), Rainbow or peacock, spider-web, mahogany. Some obsidian when sliced into a slab are opaque, translucent, or clear. Others may have patterns like swirls or lace. If you would like some, email your address.