Answer:
The dandelion took Katniss back to the school yeard years ago when she had to forage for food in the forest to feed her family.
This memory made her realize that there is hope and that everything will be alright. So, she began to get herself primed and ready for the inspection/ showcasing before the people of Panem.
Explanation:
"The Hunger Games" is a dystopian novel written by Suzanne Collins that depicts a world where there are "games" organized for the entertainment of the upper rich class while it is a matter of life and death for the 'participants'. This novel delves into the dystopic world of rich and poor, where survival depends on the success of their 'volunteers' and the efforts of the teams involved.
In chapter 4, Katniss Everdeen, the 'tribute' from District 12 alongside Peeta Mellark were on a train bound for Capitol. When she saw the dandelion, she saw the symbol of hope, hope for better things. And in the act of throwing out the biscuits, the field of dandelion took her back to the past, "in the schoolyard". It reminded her of how she managed to foraged dandelions from the forest and fed everyone with "dandelion salad". In Chapter 27, she narrates "The bright yellow that means rebirth instead of destruction. The promise that life can go on, no matter how bad our losses. That it can be good again". This yellow flower symbolizes hope, a chance for a better situation.
Then, she began getting herself ready for the Games, the make-up and the preparation to be presented before the public. This flower and the memory made her realize that there is hope and that she will be alright. So, she began to get herself be primed up for her appearance before the people of Panem.