Rita's Cafe was a pre-War restaurant around the Las Vegas area.
Rita's Cafe was a pre-War restaurant in the New Vegas area. It would seem that the company was founded by a woman named Rita, who may or may not be the woman pictured wearing a space suit in company advertising. No actual Rita's Cafe can be found in-game, but billboards praising Rita's pies can be found throughout the Mojave Wasteland.
Billboards advertising Rita's Cafe appear in Fallout: New Vegas.