Gold is a precious metal that is becoming scarcer by the minute. There are still mining operations throughout the world that are successfully extracting gold. In the US there are many professional outfits, along with hobbyists that are gold mining and profiting. Note however, there haven't been large finds in the continental US since the beginning of the 20th century.
Where in the US can I Mine?
The answer will probably be surprising to most folks. The western part of the country has thousands of places where gold is still present. These include many in the states of California, Colorado, Alaska and many others. A quick search of the internet can get the hobbyists the location of businesses that allow you to mine for gold on their property. Some modern age speculators find nuggets worth thousands of dollars at these sites. It is legal for you to go out on your own in some of these states and mine on public property. You should remember to check local laws to make sure the activity you wish to do is legal.
How Much Will I Find?
So, if there is still unmined gold in the US how much can you get? That probably depends upon how much time and effort you can put into the process. If you are a hobbyists and can only do this for a couple hours a weekend you might not have much success. If you can devote time to speculating and find a reasonable source then the answer is a good amount. You might not find a boulder size piece put panning all day can easily give you a couple hundred dollars if done in the right location. Unmined gold is still being found in the US daily, and many individuals have found a way to make their sole income from harvesting it!