Easy money
Once you gain access to the tunnel with the merchant beyond Pueblo, return to the farm area and wait for the chickens there to lay eggs. Exit and re-enter to begin the same process over again. After you fill your inventory, you can return to the nearby merchant to sell your eggs. White chicken eggs sell for 300 Pesetas, brown eggs for 600 Pesetas, and golden eggs for 3,000 Pesetas.