Considering Mildred's attitude towards poetry, poetry is best symbolized as

I'm not sure what you're looking for here. Mildred does not want him reading the poetry and makes light of it. From what she say, we'd have to surmise that she considers it worthless and a waste of time.

"Mildred snatched the book with a laugh. "Here! Read this one. No, I take it back. Here's that real funny one you read out loud today. Ladies, you won't understand a word. It goes umpty-tumptyump. Go ahead, Guy, that page, dear."