A commenter on the previous post on the Mbuti pointed out that the mango they eat is not rich is fat, but in fiber. When I looked at the data it became clear that the data from the original paper reffered to the whole fruit including the seed I think. The fruit in question is Irvingia gabonensis. Further research turned up this very interesting book on how this is used:
The book also contains information on other easily refined fats like Borneo Tallow. I suppose the myth that early humans couldn't have had access to oils is busted...but remember that couldn't doesn't mean they actually did.
I would love to try any of these "jungle butters." I recently tried a South American fatty jungle seed marketed under the name SaviSeed (Plukenetia volubilis). While I am skeptical of their claim that they have more omega-3 than salmon, since the omega-3 in the seeds is ALA, which is less usable than the DHA in salmon, they were quite tasty and an interesting candidate for agroforestry.
The dika nut unfortunately is not yet considered commercially viable, but breeders are working on varieties that could be grown faster and have easier to crack nuts.
Edit: Oh, actually I have had Dika; at Buka in Brooklyn in Ognono soup! I remember it being very good!