So it turns out that yellowjacket stings hurt a lot more than Georgia scorpion stings.
I riled up an underground wasp's nest yesterday with the riding mower. I didn't get stung and didn't get close enough after that to say anything about the kind of wasp or bee they were, but they looked way too big to have been something else like a swarm of gnats. However, I didn't see them again, even when I got (relatively) close to the same spot again.
So today I was using the push mower to get some spots that the riding mower had trouble with, and suddenly OW! What just bit my foot?

I kicked off my flip-flops, knocking my MP3 player out of my pocket in the process, and look down to see 3 or 4 yellowjackets hanging on to my pants (I'm glad I wore jeans, and jeans without any holes in them, to touch up the lawn today!). So I head back into the house, go put some cold water on my foot (which still hurts), kill another wasp which I apparently missed and which came off of me in the bathroom, and head back out. I can't find the nest, so I spray some wasp killer in a couple of spots that look like they might be it and do the rest of the lawn.
It's now an hour or so later and my foot still hurts a bit. When I got stung by one of our scorpions, it was a small sting and didn't linger. The scorpions look more dangerous, but the wasps are much worse!
I'm just glad I only got one sting. That could have seriously sucked if they'd really swarmed me.