Copper is found in the Black Forest, looks like bright solid rock mounds with golden veins.

Tin is found around the edges of the Black Forest, bumps of silver looking little mounds around the shore.

Combined(2 Copper=1 Tin) equals Bronze. Bronze opens up a bunch of new options The Cultivator is one of those options. The Cultivator 'grooms' the dirt you use it on. Once this happens, you can plat Carrots/turnip. Make sure you give them decent space otherwise they won't grow. Consider the space your character's width.