Answer:
Some commodities that became valuable as Americans expanded westward are:
Bison meat: Bison meat was so prized that they were almost became exticint due to overhunting. The Bison was once numerous in the Great Plains, but nowadays, there are much less of them, and mostly in national parks.
Gold: this applies mainly to the California Gold Rush of 1849, which was the event that attracted many immigrants from other parts of the US and the world to the state at the time.
Furs: some of the first people who went west were fur hunters, who hunted many types of furs like beaver fur, which was very valuable at the time.