I've found that it varied with me. Saltines would help for awhile, then ginger ale, then peanut butter crackers, then Coca-cola (Caffeine free works just as well.). Werther's Originals candies helped sometimes, too. Thankfully mine was truly "morning" sickness most days, so I could eat fine the rest of the day. I'm in my 15th week now, and it has just now gone away (I think--yesterday was the first day I've felt really good, and today is okay for the moment.)

Also, your doctor should be able to prescribe something for you if it is bad enough. Mine was never quite that bad, but a good friend of mine had to go on medication, as she could barely function without it.