Reed Gold Mine is an absolutely great place for a fun, informative and incredibly inexpensive trip. I lived in this area for about 10 years and never managed to check the mine out until a recent trip to see my family, and I had no idea what I was missing.
Admission to the park is FREE, and for a measly $3 per person you can also try your hand at panning for gold! There's also a gift shop with quite affordable goodies.
We walked through the cool indoor museum and learned about John Reed and the history and technology of gold mining in North Carolina during its brief boom in the 1800s. We then took the self-guided Underground Tour through some of the mining tunnels, which were cool and well-ventilated (even my somewhat claustrophobic mother had no trouble). It was pretty fascinating to be down there and think about what working conditions would have been like.
Finally we tried panning for gold. We each got a pan of dirt, sand and rocks and stood at a water-filled trough while a friendly staffer explained what to do...about 15 minutes later we were down to just sand and low and behold, I had a couple of little flakes of gold in mine! They said about 1 in 6 pans ends up with some gold, not enough to retire on or anything but still a totally cool experience.
They also do occasional programs for all ages. I definitely will come back when I'm back in NC.