Well, according to the most recent Bureau of Labor Statistics report, 1.6 million workers are at or below the federal minimum wadge. And I could break down the groups for you to show you it's more than prisoners and field workers. But seeing as you could have just googled it yourself instead of incredulously asking internet strangers for anecdotal evidence, I'll assume doing so would be a waste of my time.

Still, if you are genuinely curious, here is the report I mentioned.

Prisoners make significantly less than min wage in most cases. In my area it’s $1/day.