Comes in many different forms. I love it when you hear words that, whether technically poetry or not, just do it for you.
There is an Anglo-Saxon riddle that always makes me shiver:
I am fire-fretted and I flirt with Wind
and my limbs are light-freighted and I am lapped in flame
and I am storm-stacked and I strain to fly
and I am a grove leaf-bearing and a glowing ember.
I love the rhythmn and the soft alliteration. When I read through my own work I'm often surprised how much alliteration slips in. But, I find it works best when it is unintentional. When I use it on purpose it sounds forced and unwieldy, and turns into clumsy tongue twisters.
I heard a Willie Nelson song on the radio tonight (as you inevitably do when tuned to Radio 2, which has become our weekend listening of choice - got to face it, we are OLD now). The lyric really stuck in my head and set a story idea going:
When you dig my grave
Could you make it shallow
So I can feel the rain
It's a kind of poetry I think (certainly better than any verse wot I ever wrote).
The answer to the riddle by the way is - a beam of wood. My other favourite from the same collection is one that I like cos its funny (and rude!) rather than poetic:
Swings by his thigh a thing most magical!
Below the belt, beneath the folds
of his clothes it hangs, a hole in its front end,
stiff-set and stout, but swivels about.
Levelling the head of this hanging instrument,
its wielder hoists his hem above the knee:
it is his will to fill a well-known hole
that it fits fully when at full length.
He has often filled it before. Now he fills it again.
Now then. Calm down - its a key of course. What were you thinking?
I love a bit of Dark Age humour. Imagine them all snuggled round the fire chuckling and sniggering and someone at the back shouting out, 'Willy!'
Many were met, men of discretion
wisdom and wit, when in there walked...
Two ears it had, and one eye solo,
two feet and twelve hundred heads,
back, belly, a brace of hands
a pair of sides and shoulders and arms
and one neck. Name, please.