Most materials I find or make myself. I sell a variety of materials for making knife handles. I make knives myself and am always seeking interesting handle material. You might look all around the web site at various raw materials. But some material I cut with the knife maker in mind, that I know will work and has been cut specifically for knife makers. Most of the wood under 'raw wood' is good for knives as well, but here are some materials to glance through all in one place. Most of these materials I find or create myself so can answer questions on suitability use care etc..
Mammoth ivory chunk 1 pound 12.9 ounces.
12 x 4 around the curve by ½ inches thick. Descent deep natural colors, but has delamination and one big crack issue. Each delamination layer is stable and ¼ inch. Or could possibly restore stabilize to the full thickness if required. Crack takes an even 1 inch off the width. (an inch is a normal need for knife scales.)
Mammoth ivory chunk 1 pound 2 ounces
13 x a tapered 3-2 x about ½ inch thick. Good natural colors, Solid, no soft spots or cracks. Windows could be sanded for scrim or carving, also good knife material.