I read about the second top. It's from Papua New Guinea and was used in a ceremony of yams. Apparently there was some kind of ceremony with the tops and in the end, a man of authority would deem someone with a good harvest of exceptionally large yams. The top is made of dried coconut shells.
Great information, Joda. Do you remember where you read it?
I have these that I got in a regular (non-Ebay) auction and I guess are also from Papua New Guinea. The carving of the coconut shells is similar, but the stems are less finished and longer. One even has some paint:
I'm not sure if the stems are in the right position, with the short side on the concave side, but that's how I got them. They are easy to spin with the concave decorated side down using the fingers. But using a palm start i can spin them concave side up for several seconds.