Most things of value are going to be archeological. If you want gold you do panning.
https://www.smithsonianmag.com/smart-news/amateur-treasure-h...
And would likely be considered important archeologically.
https://en.wikipedia.org/wiki/Tara_Brooch
TL;DR finds of over 2 grams have to be given to the state (you might get it back).
Most things of value are going to be archeological. If you want gold you do panning.