After a horrible gardening accident, while suffering no physical injuries, ol' Greenfingers decided to wrap up her face in that green tape stuff that you create fake stems with...y'know, that stuff. The accident was very traumatizing you know. And she started killing people because it turns out she was crazy, and people didn't take kindly to that, so they used the nearest radioactive raygun to battle her, accidentally melding her DNA with a scarecrow.