You can't have pimento cheese without pimentos. The heart-shaped red pepper is a slightly sweeter cousin of the red bell pepper originally imported from Spain, which is why the vegetable is so often spelled pimiento. (Both spellings are correct.)
After the boll weevil decimated the Southern cotton crop early in the 20th century, the agricultural extension movement/scientists introduced the pimento crop to Georgia, which soon became the world's largest producer. That distinction has long since been lost to California, but Tennessee still holds the title of the world's largest producer of canned pimentos—and almost anyone looking to make pimento cheese is going to use those little 4-ounce jars.
It turns out the Johnson City company Moody Dunbar, which started in 1933 when schoolteacher Thomas Moody Dunbar tried to make some extra money by selling pepper seeds, is now the king of pimentos (and canned red peppers too). Some of those pimentos end up stuffed in olives, sure, but a whole lot end up in pimento cheese—especially in restaurants and the prepackaged spreads in grocery stores.
Moody Dunbar president Stanley Dunbar says, "We feel really great about it. We've been in business 78 years ... and we enjoy supplying pimentos to the retail trade." As the only domestic producer of pimentos, Dunbar says he's proud of pimento cheese's current popularity—and the spread is of course one of his favorite snacks.
"I love it! I eat it all the time. Everyone here does," Dunbar says.