I have a lot of Mexican cookbooks and as I pored through them recently, I noticed that every dried bean recipe requires a herb called epazote. The authors explain that epazote not only adds flavour; it is also known to alleviate the flatulence that often comes from eating beans.
I've never seen fresh epazote and have only used the dried herb (although if you can find the seeds, you should try to grow them - it's said to thrive in tropical and semi-tropical climates).
Initially, it's not appealing - its scent is pungent; so much so that when I brought a bag of the dried herb back to Hong Kong after a visit to the United States, I could smell its petrol-like aroma even before I opened the luggage. Fortunately, you don't need to add much of it to get the flavour and beneficial effects.
Epazote, when brewed into a tisane, is also used to rid humans and animals of intestinal worms. Store the herb in an air-tight jar so that the scent is contained.