Chamomile is a common name that is used to refer to multiple different plants in the Asteraceae (aster/daisy/sunflower) family. Here's a link to the Wikipedia article that would be a good place to start finding more info.

http://en.wikipedia.org/wiki/Matricaria_discoidea

You can find all the pictures you'd ever want on the web. Here's a link to some chamomiles on Dave's Garden. Most have pictures attached. The pictures and info on Dave's Garden is sometimes incorrect, so don't count on everything being 100% accurate. Always double check information you get from that site.

http://davesgarden.com/guides/pf/search.php?q=Chamomile&Search=Search+PlantFiles