Instead of vinegar, try citric acid crystals. You can get them online quite easily. They are cheap, easy to store, and no stank!
As for dyes, I have used black walnut that I collect to eat. Wear gloves! Crush up the green husk and boil it until it's black black black. Strain out the bits and simmer the yarn in the liquid - you get a nice rich brown. Works on hair, too!