Advice on dye

Has anyone used the dying method with berries for a purple color? If so what and how did you use?
I’m also curious if anyone has any ideas for more of a charcoal look with natural dye elements?
I have a bear skull that’s got a dingy yellow tint. Getting ready to whiten some before the dye process. I’m looking for something not too dark that I can hand paint some details over. (If that helps).