I read somewhere that the peanut superstition has origins at IMS. The way I was told, this was back when folks (fans) used to build their own scaffolding over their passenger cars to watch from the infield. It seems that one year there was a delay, and one (or more) of the race cars was parked under or near some of the scaffolding until the race was run. On raceday, this particular car had mechanical trouble, and pieces of peanut shells were found in the intake. So far as I am concerned, the supertition is aimed more at peanuts in the shell than the other.