Forager has many puzzles, some are easy and some are quite difficult. Luckily, this is one of the easy ones. You can view a load of puzzle guides, as well as other Forager guides in our dedicated section here.
In the Desert Biome, you will find a sign which states “There is secret where the flowers don’t live”. It’s a riddle, and what I can tell you is that you will require a shovel, and to get access to the shovel, you will need to unlock the Farming Skill found under the Foraging tree.

Take a look at the area just above the sign, you will see 4 points. On 3 of these points are flowers, whilst one of the points is empty. This is the answer to the riddle, as flowers don’t live there.

Head to this empty patch with your shovel and dig the area. A Big Chest will fall from the sky onto the patch and you will have completed the puzzle. Inside the chest, you’ll find a Spirit Orb.
Depending on your current progress into the game, I’d recommend you spend the Spirit Orb on a level up if XP gain feels slow. Otherwise, save it for a later point in the game for when you might really need it.