German Chamomile is really easy to grow ... like weed easy: it will reseed all over if you let it. You could just grow your own, then you can know it's safe. Dandelions are actual weeds, and herbs can often be purchased as plants at some grocery stores or plant nurseries ... they're intended for human consumption, so they should be safe. Of course, then you'd have to dry it yourself.
If you want it all dried and packaged for you, you could try your local petco or petsmart ... just make sure to read the ingredients (they're not always great at advertising for the correct animal on their products and often carry some junk-food products mixed in with the decent ones). Alternatively, check out Sweet Meadow Farms; their products tend to be easier to find at smaller shops than the big chains, or depending on where in Massachusetts you are, you might be able to go to the actual farm - it's in Sherborn (about halfway between Worcester and Boston, near Framingham).
