Flower in Her Hair Trophy in Last Day of June

Right at the beginning of the game, as soon as you gain control of Carl, exit the pier. Right when your feet hit land, there will be a rock in front of you with two flowers around it. If needed, there are plenty of flowers near the small playground slightly uphill. Approach one of the flowers and pick it up with as soon as you are given the prompt to do so.

Once you have the flower in hand, go back to the end of the pier where June is. Approach her and when given the prompt, press to give her the flower.