Dave, I'm going to put a small amount of ground black walnut hull in an envelope for you and post it off to you. It's a powder traditionally used to make a deep brown or black dye and can by either used to dye cloth or leather.
To make a leather dye, you'll need a half bottle of the cheapest vodka you can find. You put the dye powder in the vodka and give it a shake. Leave it in there for a week or so, shaking a couple of times every day. After a week, strain it through a coffee filter or double layer of kitchen paper to filter out the sediment. That'll give you a dark brown dye. To make black dye, do the same but add a walnut size lump of fine steel wool (shredded). The tanin in the walnut hull will react with the steel and make it jet black.
Check on the 'net' for other techniques for making walnut hull dye as well as the way I've described it is not the only way. Also Toddy might have a better way of making leather dye using walnut husk. Did the other package arrive by the way?
Eric