The original Potato Head was a bunch of accessories that attached to a real potato with pins. I'm not sure if the safety aspect of sharp objects as a kid's toy was the only thing that prompted the change to a plastic body with pegs, since kids were also playing with potatoes that were either drying out, getting moldy, or decomposing.
However, I do remember watching an episode of Yan Can Cook years ago where Martin Yan was having fun with a taro root, and he had a special one decorated with Mr Potato Head pieces that he called "Mr Taro Head".