I've found that prunes, pears, and peas all help with the constipation. I try to give my son at least 2 of those a day. We usually do oatmeal with 2-3 oz of prunes for breakfast and then 2-3 oz of peas at either lunch or dinner (and now that I think of it, pears at the other meal- lunch or dinner). It seems to help. Without this, he was doing nothing but little pebbles (I call them cat turds, that's what they look like). Now it's softer and he goes several times a day.
I had no idea I could spend so much time thinking and talking about bowel regularity!