If you want ivory, you could consider Mammoth ivory. There has been no recorded Mammoth kill for the ivory in the recent past
I am not sure about Indiana or USA as a whole but in Europe (they are normally really strict compared to USA), Mommoth ivory is perfectly legal. There, price and availability is more the problem. And Mammoth ivory is not really white, but rather cream or even light blue because of the sediments where the tusk was laying a few thousand years.
In knife making, Mommoth ivory is very common. It can be distinguished under UV light from elephant as the Schrager lines have a different angle.
Regards
Gerhard