CS, the popular caveat against taking any herbs during pregnancy is bunk and based on ignorance on the part of the medical community. Any acupuncturist who has been trained in Chinese medical gynecology knows that there are only a few herbs that cannot be taken during pregnancy. Traditionally, herbal medicines have been used throughout pregnancy with great success, for specific problems that pertain to pregnancy. (The question is not, can herbs be taken? but rather, what herbs are appropriate for which condition.) It's a matter of finding a practitioner who has been properly trained in herbology as it relates to gynecological issues.
And, commercial teas like Good Earth do not contain large enough amounts of herbs to have strong therapeutic effects, so they are likely safe.
If the nausea doesn't subside, acupuncture has a great track record for relieving it during pregnancy--even without herbs!