From my reading tonight, it appears there is no official RDA for Fiber, but there is the "Percent Daily Values" on food labels in the US that has 25 grams as the daily goal.
According to The Mayo Clinic:
Boosting your fiber intake
How much fiber do you need each day? The National Academy of Sciences' Institute of Medicine, which provides science-based advice on matters of medicine and health, gives the following daily recommendations for adults:
Women:
Age 50 and younger: 25 grams
Age 51 and older: 21 grams
Men:
Age 50 and younger: 38 grams
Age 51 and older: 30 grams
For my 25 grams, I usually end up relying on stuff like "Fiber One" cereal, but if you Google "mayo clinic fiber", they have all kinds of healthy recommendations to boost your intake, including stuff not out of a cardboard box