Who said how now brown cow?

The phrase "How now, brown cow?" doesn't have a specific, attributed origin. It's a traditional children's rhyme and is believed to be a nonsensical phrase, likely originating from folklore.

The phrase is often used to teach children about pronunciation and rhythm, and is also commonly used in games and nursery rhymes.

It's important to note that the phrase is not attributed to any particular person, but rather is a part of a shared cultural heritage.