I believe you mean "poppy seed buns." Born and raised in Chicago, drove a cab for four years, stopped at scores of hot dog stands. Never heard of a pepper seed bun.
Willie's Wee Nee Wagon was on Crawford, just south of 159th. Some ex drug guy bought it and changed the name, I believe.
You seem to like coming on as a local of this or that city, but you usually seem to fall a bit short in actual native knowledge of a given locale. Where did you actually grow up? What cities have you actually lived in?