I don't much like ham myself either. I don't know why... We usually have it on Christmas or Thanksgiving etc, but I never much like it, especially compared to Turkey.
Mushrooms I don't really care for, but theres worse I suppose. On most pizzas they're mostly tasteless for instance, but I still don't like the texture to them.
Onions I don't like. Onion rings are great.
I don't much care for Fish either. But at the same time, there are many different kinds of fish and many ways to prepare. Some is better then others, some I can't stand though.
Lets see what else... I'm not big on cake, and rarely would eat it at a party, but I don't exactly dislike it I suppose.