" I have talked to several people about this and they all say ,that unless an area is deemed "archaeologically" important or is otherwise posted, I should be ok to dig there. I'm gonna hunt till told otherwise "
This is the logical approach, if you ask me. There are SCORES of places around the USA, under all sorts of jurisdictions (various city, county, state, and fed. agencies), that truth be told, no one really cares less, unless you're being a nuisance, snooping into obvious historic monuments, etc... But does that mean that if you asked long enough, and hard enough, that you might not find someone in the bureaucracy to tell you "no"? Of course not. You can ALWAYS find someone to tell you "no", even at the most innocuous of sand boxes, if you ask long enough and hard enough of enough bureacrats. All they need to do is leaf through the minutia, to find something to address your "pressing question" (disturbing foilage, harming earthworms, non-collecting verbage, etc...) and presto: you'll get a "no" where quite frankly, no one would probably have ever cared or noticed you.
And as for the TVA "reviewing their policies", how much you want to make a bet that the reason for this "policy review", is the numerous people going in and seeking clarifications, sanctions, asking questions (ie.: "can I keep this 51 yr. old penny I found?") etc.... It's a vicious circle, because if you try to tell these skittish folks "just go", they will invariably point out threads just like this, as the very reason they think they need to go asking. Thus merely perpetuating the vicious circles of new rules written and clarified to "address their pressing issues". Aaaarrggghhhh.