The imagery of "two fallen branches in the shape of a heart" signifies a serendipitous discovery of nature mirroring the symbol of love. It's a visual representation of love's presence in the world around us.
The phrase "thought of you" conveys that the sight of this heart-shaped formation triggered thoughts and feelings about a particular person. It implies that the person holds a special place in the speaker's heart, and their connection is associated with love and affection.
In essence, this statement celebrates the idea that love can manifest in the world in subtle and beautiful ways, even in the form of fallen branches. It conveys the notion that love is a pervasive and meaningful force that can be found in the most unexpected moments, reminding us of the special people who hold a place in our hearts.