Are any herbal supplements tested by the government?

No: The federal drug administration (fda) does not test drugs or supplements. The fda evaluates research studies on medications to make sure they are effective and safe. Supplements are regulated under a separate law and don't have to be shown to be effective, but the manufacturers can't make claims about how they affect health.

Usually not: If your question is about finding high quality herbal supplements, the brand nature's way (purple top) manufactures according to standards from the german commission e (published between 1984 and 1994) which formed the basis for medical prescribing of herbs in germany. It is best to look for either whole herb or standardized extracts. I also use gaia, herbsetc, eclectic institute and herbpharm.