Do any fruits have beneficial fiber, or only vegetables and grains do?

Whole fruits. Whole fruits have lots of fiber, fruit juice by itself often has none. So if fiber is what you want, eat an apple, or pear, or peach, or any other & skip the juice bottle.
Fiber sources. Fiber is found in fruits (blueberries, cranberries, apples), vegetables (broccoli, radicchio, endive, spinach), whole-grain breads (whole-GRAIN more than whole-WHEAT) and some breakfast cereals. Fiber supplements exist as well. It's always better to include all sources of fiber as part of a healthy, varied meal plan. 35 grams daily for women, 50 for men. And drink lots of water.