In the game there are different collections. By making them, you get rare resources that you will need in the game, such as salt, nails, water, coins, energy, etc.
If you need a collection item, you can find it by visiting your neighbours' settlements. When you visit your friends, open the Collection tab and click on the items you look, you'll get a tip.

Also, please notice that any item from the 'Chance to Get' drops randomly.

With love,
Your Farland Team