Apples, pears or plums - natures constipation cure. I ate an apple every day during my pregnancy and never got constipated. I give my son applesauce when his poop gets real firm, and within two bowel movements it's back to normal.
If he doesn't like apples, or applesauce - I jazzed up my daily apple by coring it, putting it in a shallow bowl, putting a little butter inside the hole left by the core, and packed it with brown sugar... microwave for a minute at a time until it's soft and warm, and slice it up and serve warm - YUMMY!