Choose a nursery rhyme or other short poem, verse or proverb. (Choose something old enough to be in the public domain.) Let that nursery rhyme inspire a flash, but make your story about something beyond the situation and characters in the rhyme.
You can keep the nursery rhyme at the beginning of your piece, or interweave your prose with the lines of verse.
To get you started, here is a list of nursery rhymes.
If you’re submitting this to us, make sure to note that this is a response to Prompt 1: Nursery Rhymes, and make sure you let us know what nursery rhyme, poem or proverb inspired your story if it's not included in your final piece.