Some interesting poetry themes are: things found in nature (grass, trees, flower, river, etc.), an emotion (rapture, grief, peace, etc.), a feeling when doing something (such as running, swimming, taking a walk, hugging, drawing, etc.).
I think another good theme is just poems in which the writer is putting themself in another person's, or thing's, or place's shoes. Because those poems are very interesting. It makes you see things from a different point of view.
Have fun with your assignment, wish I had it!
