The line "I never saw a purple cow" is the beginning of a poem by what author?

I know the Purple Cow poem but never heard who wrote it. I also know of "the Goops" (nasty, ill-mannered children who are ashame to their parents) through their inclusion in volume 1 of 'The Better Homes and Gardens Storybook' from the mid-50s. Both volumes are delightful, the 2nd one comprising longer, more advanced stories for slightly older children. I have given mine to my great nephew. :)

it was a good poem but too short!!