It was a strange choice to silver-plate this, but it's definitely one of the four shiniest turnips you've ever seen. And it's balanced such that you can wear it on your head! All hail the Monarch of Turnips!
You must have a Dusty turnip in your inventory to have the option to get the Turnip Crown. There is only one such turnip, given at the beginning of the game, and it can be eaten before discovering the option to plate it.
You can give it to Norton at the end of the game so he doesn't steal the train, which could be done for a faster ending or speed runs.
- For some reason, the Turnip Crown can be silver plated, even though the Turnip Crown is already a silver plated turnip.