What's your favorite poem? (And if you don't have one, why?)

In keeping with June's National Blog Posting Month or NaBloPoMo and their fun daily writing prompts, today's prompt is, "What's your favorite poem? (And if you don't have one, why?)".

I don't have a favourite poem. I don't particularly enjoy poetry as I don't understand it. I recall in one of my university english classes trying to convince the group that I thought the poet was comparing the ocean lapping against the beach as the acid of your stomach eating away at your stomach lining and thus causing an ulcer. I got weird looks but that's what the imagery said to me. How can they tell someone that their interpretation is wrong (or out there)? I do enjoy epic poems but they are usually in olde english so they are hard to concentrate on.

Now to you, what's your favorite poem? (And if you don't have one, why?)