To work in or work with? Either way it's gross but the distinction is important.

Picasso had his Blue Period. Your daughter is clearly having her Poo Period.

"Poo period" sounds like something completely different (and even more disgusting, no less).

I wonder how medium will impact style. I could imagine a tendency towards pointillism after eating corn.

If a blue canvas with a white line down the middle is considered artwork, I'm sure pretty much anything including shit itself can be one too.

She could be the next Poocaso

Most art these days is shit — at least your daughter is literal.

She’ll be a modern art master in no time