Pick a word. Any word. Don’t think about rhyming.
Write it down. Look up at the ceiling or at the sky, whichever is more accessible. Don’t strain.
If you wrote ‘peony’, imagine a heavy pink flower after a rain.
Peonies make me thinks of grandmas. (That’s fairly unique)
Grandmas smell of kitchens and apple pies. (That’s a cliché. This means that most people would think that Grandmas smell of kitchen and apple pies.)
Grandma that rides a horse might be fairly unique.
I don’t know where she’d ride her horse in the middle of the night.