Generally speaking, it seems that beans and many veggies are high in fiber.  Most fruits I searched were in the 10-20% range. Here are my initial findings:

 - Broccoli (~46%)
 - Black Beans (~37%)
 - Pinto Beans (~34%)
 - Peas (~34%)
 - Cabbage (~34%)
 - Bran (~23%)
 - Barley (~23%)

* Percentages based on Dietary Fiber / Total Carbs on nutritional labels