There is a common saying/belief here in Kashmir regarding the lotus root stem. Lotus root stem (nadru in the Kashmiri language) is eaten here as food and has fibres. The belief is that Faatimah, may Allaah be pleased with her, supposedly threw some fibre from her spinning wheel into water, and that it is therefrom that fibres grew into the lotus stem. Also, they say that she made some supplication for the lotus stem and spinning wheel. Is there any authenticity in these beliefs?

All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ʻalayhi wa sallam, is His slave and Messenger. 

The story mentioned in the question has no basis. It is clearly a mere myth.

Allaah knows best.