White Castle may seem like it’s on the bottom rung of the fast food ladder, but as arguably one of the most innovative restaurants in modern history, it should be known for more than just its famous White Castle sliders. Although the iconic paper caps you see on fast food workers – especially at retro-style joints like In-N-Out – may seem like a widespread industry standard, they can all be traced back to White Castle. What’s more, the burger chain (more specifically its co-founder, Edgar Waldo “Billy” Ingram) is responsible for distributing the first-ever paper food service hats.