Narethil Root
Found alongside small streams of water, where the stream makes a bend and the banks are covered in brushes and trees, one can find a small, slender, pale-green plant with silver-veined leaves and ruby-coloured roots. The upper part of the plant is, for most purposes, worthless, although it can be dried and turned into some decent tea; it's the root that is most sought after.
The roots, when they are dried out and ground into a fine powder, can be mixed into wine, mead or strongly flavoured tea as the roots have a strong aftertaste, but drinking this powder can be used as a contraceptive, to prevent or at the minimum lower the chance of pregnancy.
Its role in society stretches back a long time, and it's believed that most cultures know of the plant and its particular use and among the Crienia it's believed that the knowledge came from the elven tribe that merged with the humans. Knowledge of the root and its ability is, for the most part, passed along orally between the village healers and in some regions, the plant is known as "Moon's Veil", and it's believed that if one drinks it under moonlight, the effects will be enhanced.
During the time of the Ancient Empire the use of the plant among the peasants was forbidden, and if one was found to have it, they would be dragged off to prison or worse, given over to the mages. Following the fall of the Ancient Empire, the use of the plant to some degree was lost following the chaos in the Empires aftermath, but as time went on, the knowledge resurfaced and spread along the new trade routes.
The plant itself is somewhat rare, it needs the right conditions to grow, its possible to cultivate them in small amounts and temples typically have a small amount growing in their gardens. Among traders and smuglers its a prized commodity as one crate of the powder can bring in several months worth of wages for a regular worker, traders sometimes disguse the crates among other spices and herbs to avoid taxes and or theft.
In the wild, spots where the plant grow are kept secret to avoid theft but most importantly to prevent overharvesting.

Great little article that adds a lot of depth to your world. I like that you can still use the leaves in tea, even though they don't have contraceptive properties.
Explore Etrea | WorldEmber 2025
Thank you :) Now I need a plant or something that does the opposite ;)