There are two varieties of chamomille, German and Roman. I have both growing on my place in the same bed. I just use whichever is in flower and don’t fuss about separating them.
German:
Roman:

The German is a self-seeding annual. The Roman is a perennial.
Both are good medicinally. The German makes more flowers. The Roman is a better emmenagogue.
Don’t take either during pregnancy.
It’s most famous for it’s calming sedating “Bedtime Tea” effects. It’s excellent for stress reduction.
I use it for all the time for gastrointestinal disorders. It’s especially good for GI problems caused by or accompanied by nervous issues or stress.
Given with a little ginger it’s good for menstrual cramps.
I’ve also used it for colicky babies (usually combined with catnip). I have nine daughters several of whom are reproducing these days…I know whereof I speak. 🙂
Patrick
Don't use herbs or combine herbs with medications or use them during lactation or pregnancy without talking with your healthcare provider.