Herbs can be found in the overworld in many different biomes. They can't be bonemealed, but they can spread occasionally when Bees drop pollen on them:

Minty Blends adds some cute flowers, too! The ancient Hortensia can have a few different colours depending on the location it was grown in.

The Kettle can blend herbs and flowers together, combining their effects. Some blends may produce special teas. It needs its burner to be lit with a Flint and Steel to start brewing:

Censers apply their herbal effects in a radius around the user. They can be lit while holding one with a Flint and Steel in the offhand: