Where are these people from?

I live on the west coast, but am driving across the country. Around the west side of Texas, I started hearing people with strange accents - similar to Americans but they sound less intelligent. I've talked to people from all over the world and am always fascinated with accents, so in Arkansas I finally broke down and asked one what country she was from. She just stared at me blankly, neither of us knew what to say...like she was embarrassed or something!

It seems every other person has one of these accents, so is there a large consentration of immigrants from a specific country in these states (Texas, Oklahoma, Arkansas)? What country could they be from?