If your good at writing poems you can write a spell, but without knowing what the poems consist of we can't really tell you if they can be used as spells. There is no rule that says a spell has to rhyme but I'm a spontaneous rhymer meaning I find rhyming easy though poems and rhyming aren't exactly the same, poems being more complex than a simple rhyme. At any rate I think spells that rhyme are a great way to channel your energy and focus your mind on the desired outcome.
I love poetry and write lots of it. Being able to does help greatly with writing spells. However, when writing a spell, you need to be exact and clear on what it is that you want from the spell.
When writing poetry we tend to be a little abstract in our writing because it is our emotions that takes over. When doing a spell we have to be much clearer and level headed. In spell casting we want to direct our energy to do whatever it is we want it to do. This needs to be very clear and precise.
There is no good on doing all the work that goes into working a spell & building our energy to the point where we will send it out on a mission if that mission (intent)isn't clear as a bell.
Poetry has really helped me write spells but I wouldn't take a poem that I have written and try to work a spell with it. Poetry is to messy for it. I guess if you write poetry that is very clear, clean and precise you may find it easy to work a spell with. I don't have that sought of writing style when I write poetry. Everyone is different though:) Good luck!