Leafy green vegetables.
Many fruits, grains and vegetables are high in fibre, for instance:- Apples- Oat bran- Bananas- Apricots- Peaches- Whole-grain breads- Cereals- Rolled oats- Muslix cereal- Lettuce- Carrots- Celery
Whole grain
wholegrain bread, wholewheat pasta, branflakes and brown rice
The sources for food are animal and vegetable. You'll need to be more specific to get a better answer.