well lard and salad oil are good choices....
just kidding, those have a lot of calories
but they are unhealthy to consume a shit load
i would stick with
pasta, whole wheat bread, potatos, rice, oatmeal
for carbs (veggies are healthy but low carbs)
lean meats like steak, chicken, fish for protein
flax seed oil, peanut butter like you said, olive oil and such
and if you just want to bulk and don't care
burgerking is the best but i don't suggest that route
those are just basic shit