I was going to mention the Steve Goodman song, but a couple of people beat me to it. Another that comes to mind is John Fogerty's "Centerfield"; not exactly a folk song by most definitions, but neither are a number of the songs mentioned here (of course, you could rework it into more of a folk or bluegrass style if you wanted). In the late 1980s I used to play in a band that had a once-a-week gig at a bar right next to Fenway Park in Boston (home of the Red Sox). In the summertime, we would see a huge rush of people coming in the door when the game let out, whereupon we would stop whatever we had been playing and launch into "Centerfield". Win or lose, it helped set the mood.