In poetry, “sentence” is a relative term. Sentences can even be as short as one word. Try to keep your grammar rules loose when writing any form of poetry.
Prose poetry can often be mistaken for short stories, although the writing style is slightly less factual and more poetic.
Prose poetry can look like many different things, so try not to get boxed in by looking at examples.
Try writing about the first birthday you can remember, or your first day of school.
Try writing about the Civil War, or the Civil Rights Movement. If you are a history buff, this would be a particularly fun project. Feel free to insert yourself into the historical event, or imagine what it would have been like to be there.
You can try talking to the object, or telling other people about how much it means to you. Try an object that you have an emotional connection with as an easy place to start.
Try to choose short words that are easy to rhyme with. For example, “Be Drunk” by Charles Baudelaire has a line in it that goes, “everything that is groaning, everything that is rolling. ”