Yes, every day, Harri, don't you? Wir Amis sind ja ziemlich durchgeknallt ...
No, seriously, it's illegal to buy or sell fireworks in most US cities, because of the fire danger. Permits are restricted to public fireworks shows, which have to be in a safe area and follow safety guidelines.
So people who sell individual fireworks tend to have stands just a mile or two outside city limits, and people who want to shoot off illegal fireworks on holidays tend to buy them and discreetly bring them in. The fireworks stands, or now often fireworks warehouses, are really only open for a few weeks before each holiday. Mostly the 4th of July, but also sometimes other patriotic ones like Memorial Day, and in areas with many Hispanics, definitely New Year's.
In my state at least; see what others say.
Roadside fruit and vegetable stands are also probably less common now than in my childhood. Nowadays, the trend seems to have changed to the farmers' market, which is like a very small version of a European weekly market day.
If travel goes back toward car trips thanks to the pandemic, though, who knows, roadside stands could become more popular again. You do still sometimes see just an individual farmer selling things out of the back of his pickup truck, under a shade tree. I remember when that was the best place to find really fresh watermelon, or white corn. (-: