Camomile

I am allergic to it so do not grow or drink it, but James Wong suggests using German Chamomile rather than Roman.
Matricaria recutita.

The german one is only an annual, so could be harder to keep growing unless you have a nice light soil which would enable self-seeding. I would go for the perennial roman personally. Anthemis nobilis, or Chamaemelum ­nobile. However, you may get more flowers from the annual variety - I suppose it depends on how much space you are willing to dedicate to it.

Don't buy treneague - that is the non-flowering lawn variety! Also a roman perennial.