GalaxyLad mentions a golden coconut in his Diorama quest. Then there was another NPC--and for the life of me, I don't remember who--who said that her adventuresome grandfather told her stories about yellow coconuts, which he called 'golden' and found in the Dry Isles. I think it may have been MadamPortsMouth in the Angled Isle dockhouse, but now that I've finished her quest she won't say anything else and I'm not really certain.
For the record, I have harvested every palm tree on every dry isle, and found nothing. Am I crazy, or has anyone else heard about this?