Vegetable ivory is a product made from the very hard white endosperm of the seeds of certain palm trees. Vegetable ivory is named for its resemblance to elephant ivory.

http://en.wikipedia.org/wiki/Vegetable_ivory

I don't know how you tell the difference or how you would even

convince ebay that it was vegetable ivory.

You would have to have excellent provenance I would imagine.

Maybe try listing as palm tree seed carving - Phytelephas carving??     

Dunno,  Sorry.

http://en.wikipedia.org/wiki/Phytelephas

Maybe someone else will come along who knows more