In the townhall in the beginning, you're given the "job" to go investigate the graveyard and that you'll get 50 gold for every 5 skulls brought back. I've got 7 in one of my character's inventory. How do I give them to him / do the exchange for the gold?

Thanks

just talk to the Mayor.. wait a little as he talks to you and he will reward you for each set of 5. Don't change topics until he stops giving you exp. and gold (he'll say something like "My you have been busy").
It doesn't seem like anyone in specfic needs to talk to him, as long as you have the skulls