A $29.50 bowl of shrimp ’n’ grits, bringing together head-on shrimp, house-made andouille sausage, and sweet-onion ravigote, is the most popular dish at Jeff Buben’s Vidalia. A few blocks away, a humbler rendition of the low-country specialty appears most Thursdays at C.F. Folks, a feisty downtown lunch institution. The shrimp aren’t as photogenic, the sausage isn’t house-made, and instead of ravigote there’s a white-wine sauce, but it’s a tasty, generous plate for $11.95.