Flowers can make you happy by triggering your happy brain chemicals.
Happy Brain Chemicals
Dopamine is triggered by the expectation of a reward. Flowers were a huge reward signal in the world our brain evolved in because they marked the coming of abundance after a hungry winter. Today we have enough to eat all year round so we don’t consciously link flowers with food. However, the blossoming of a flower triggers the sense that something special is coming because it triggers dopamine.