Hey shootist, I'm having a hard time understanding your concern about authenticity, you said that you found it while metal detecting, reproductions and fakes aren't laying out there in the dirt, they're in collections and on eBay and other internet sites etc.. If you found it as said it's got a round hole going through it (all the way if the hole was finished)). Because it is a"pick" style Bannerstone the hole is all but guaranteed to be "solid drilled" rather than "hollow reed drilled", that means no systematic thread scars in the hole.
Better pictures would be great too, just so we can see what you found better, they are pretty poor pictures.
There is an Artifact Show coming up in June at Lebanon, IN, you might want to check it out and show your piece to the collectors there, I'm sure they'd be interested in seeing it. I think that's only a half hour or so drive from your location.