Tagua nuts come from a palm tree, which is commonly known as tagua palm and ivory-nut palm (Phytelephas aequatorialis) The nuts are a main source of vegetable ivory, or tagua, a botanical alternative to ivory. This palm is found in the tropical rainforests of South America, especially in Ecuador.
Tagua nuts can be cut, carved, drilled, sanded and polished just like ivory. Even though only few pipemakers use them for shank extensions e.c. In South America the nuts are used to make pipe bowls.
Link to Wikipedia on Tagua palm tree.