<<Disclaimer: Verify this information before applying it to your situation.>>

How about fresh fruits and vegetables?  Apples, pears, celery come to mind
right away, but I don't have data to hand. Oh, yeah, and prunes and raisins.

According to the bags I have in front of me, one medium potato has 2g, or 9%
of the RDA for fiber.  A 3-tablespoon (unpopped) serving of popcorn contains
4g, or 16% of the RDA.

Dried peas and beans have tons o' fiber, and the added advantage of making a
complete protein when combined with rice and corn.  (Once again, from the
labels I have in the house:  Navy beans - 12g, or 48%;  Pinto beans - 14g,
or 56%;  Lentils - 9g, or 36% for a 1/4 cup [dry] serving.)

Finally, I think trying to use brown rice instead of white will increase
fiber intake, but I don't have the paper to prove it.

Hope this helps.
Sherry Hintze in Newport, North Carolina