The metal detector I ordered from Amazon using Purse (affiliate link!) at a 23% discount, that is.
It arrived today.
I tested it on a couple of known metal locations around the house, and it beeped.
Then I took it to the spot in the yard where I dreamed I found old Spanish pieces of eight*, and it beeped some more. Haven't found whatever's down there yet. Lots of tree roots to dig around. But it's beeping where I know there's metal, still not beeping where I know there's no metal, and finding metal I didn't know was there (an old bolt in the yard, after I got tired of digging and decided to sweep around elsewhere just to make sure I wasn't fooling myself). So I think there's metal there.
I'm fairly confident I'll find some stuff that's at least fairly old in the area I'm focusing on. It's near some trees that separate my lot from my neighbor's. My neighbor had a tree guy tell her they were at least 200 years old, possibly older. If that's true, they were already big, mature trees as of the Civil War. I suspect they were a dividing line between plantations or plantation fields, or perhaps fronted property on a now long-gone road, and that it's reasonable to believe that at some point, people congregated to work, rest, party, whatever in their shade. And dropped stuff.
* No, I don't think that my dreams possess special predictive/locative powers. But that dream (probably 4-5 years ago) got me thinking about seeing what might be buried under the place where I live. The itch never went away, I finally decided to scratch it, and the dream location seemed both an appropriate and otherwise practical place to start.