I'm actually quite surprised at your reaction to eating at least a cup of oats a day.
I've seen numerous mass gaining diets and oats are among the basic foods that are included in all of them. And most of the time they are recommended more than a cup a day.
Edit: I found a couple articles which suggests oats.
1.5 cups in the morning -
http://www.bodybuilding.com/guides/m...ding/nutrition
2 cups in the morning -
http://www.bodybuilding.com/fun/smar...-diet-tips.htm
says oats provide slow digesting carbs -
http://www.bodybuilding.com/fun/musc...ou-jacked.html