Are you talking about 'Mexican Petunias'? I did a search online, came up with this picture....

Here is a link that might be useful:

No they aren't Mexican Petunias.They are an old fashioned petunia. We see them around old farm's in the Foley area. Mostely seem to be in shaded areas and get about a foot tall. All I have seen are deep red, lilac, or white. Don't kow how I ended up with this purple and white striped one. I do have some Mexican Peunias in my garden tho. I love them.

I have a bed with some of the heirloom petunias & they reseed every year. This is the 4 yr I have had them. Sometimes mine bloom in pink, sometimes purple & sometimes white, or all three. They have bloomed in two colors & in different shades of purple but I have never thought about where different colors were on the same plant. I will have to check that out. Betty