Dramamine (dimenhydrinate) Over the counter motion sickness medications work well for morning sickness. You can also take vitamin b6 supplements. Small frequent meals are also beneficial.
Ginger, b6. Some of the "natural" things that my paitients have had success with are ginger, and lemon. Avoid the ginger tablets, it is better in food/drink items. Vitamin b6 in combination with doxylamine (in the sleep aid unisom) remakes bendectin, a commonly used agent for early pregnancy. The key for breaking the cycle is to stay hydrated, and if you can't keep liquids down you should see a doctor.