Yeah found all sorts - Roman denarii, hammered silver coins, bits of gold here and there, lots of bronze and copper coins and obviously mountains of crap/trash.
It's maybe something I'd look at again in another 10 years as I'm a history buff and like the outdoors, but I don't have the time to make it worthwhile. The problem in the UK is really getting permissions and land. You mostly have to join a detecting club and/or organised rallies. What you find here is that people want to take it up, they buy a detector, and then they have nowhere they can use it and sell it. You always need permission of the land owner and there is very little common land left in England at least. Beaches can be an exception, but that to me is just hunting for lost change rather than anything tangible.
I imagine this is irrelevant to you, as you say, it must be very different in the US. You need to commit time to it but you'll know pretty quickly whether walking around for hours waving your thing about is for you