The rainbow puzzle in Forager is one of the very first puzzles players will encounter in the game. This puzzle appears on the player's first island land, and the player will need to destroy a series of mushrooms to solve it.
However, destroying the mushrooms in any order won't due, so you will need to do it in a specific order. This order follows the colors that appear on the rainbow, so to solve the puzzle, destroy these mushrooms in the following order.
You can find all of these mushrooms in the area around the rainbow puzzle, but you may need to clear the area of obstacles. The reason why is that trees and ores, and other objects might be blocking you from seeing the mushrooms, so we recommend removing all of them beforehand.
Once the area is cleared, you should be able to locate all of the different colored mushrooms and destroy them. When you have done so, you will complete the puzzle and receive a chest that will contain a ton of good loot inside. For example, you may receive a spirit orb or one of the many artifacts in the game as a reward.
For more on Forager, check out How to get Paper in Forager and How to Solve the Skull Maze in Forager | Map, Chests, and Braziers Guide