Two foods that work great for me are sweet potatoes (yams) and bran cereals, especially bran flakes.
Prunes are pretty good, but I prefer fresh plums. Prunes are dried plums. I do not like the texture of prunes and am not crazy about the flavor. But fresh plums I find refreshing and delicious, the darker skin the better. I am on many medications which cause constipation, so this is a problem I must work on constantly. Also, drink plenty of fluids.