Mutations DO rarely occur; there are some that have been isolated and stabilized, notably 'dizzy', 'ducksfoot', 'aussie bastard', and 'maple leaf'. However, they are not too common, and the really weird ones are only just now being bred to the point where they are reliably 'drug grade', so it's unlikely you found those in your bag.
Look at peoples' grow logs to see what young seedlings look like.