Before pregnancy, I ate mostly healthy fats (like oils and full fat dairy), lots of veggies, and protein. I've been fairly sick this pregnancy, and very few of the foods that I normally eat work. I dread having to find something to eat that will stay down and not aggravate the nausea, especially later in the day when I feel worse. Anything with fat really doesn't work. The best foods I've found are yogurt, fruits, saltines, sweet potatoes, low fat cheese in moderation, maybe eggs when I'm feeling better. I need to put some sort of protein with the carbs, because eating a ton of straight carbs also doesn't work great.
I'd love to hear what worked for others... could definitely use more ideas.