I agree, it can be hard to get enough fiber, especially when you are trying to keep the carbs under control. It is a real battle for me. I almost always get my recommended veggies and fruit, but even then can't reach 25g without some sort of supplement.
Beans, and other legumes like edemame (soybeans) have lots of fiber and since (unlike Cassie) I love them I tend to rely heavily on beans. Oatmeal is a great source, although it is usually a breakfast treat I skip when I'm trying to drop pounds.
I will often resort to supplements like metamucile. Staves of the hungrys for a while, adds 5 to 10 g fiber, helps lower bad cholesterol, and keeps the lower GI tract running smooth. I also use Fiber One products as sweet treats rather than a cookie or other sweet (assuming I have room in the calorie balance).
Spend some time search the grocery shelves. You may come up with some unique ideas of your own!