This is because "riens" is a French word, and English rhyming patterns don't always align with French pronunciation.
If you're looking for words that sound similar or have a similar meaning, here are some options:
Similar Sound:
* means
* teens
* greens
* beans
* queens
Similar Meaning:
* nothing
* nought
* none
* zero
* zilch
Keep in mind that these words won't rhyme perfectly with "riens" but may be suitable depending on your specific context.