Jimmy Cross seems obsessed with Martha, a girl he was interested in back home, while he is serving as a lieutenant in Vietnam. We can tell from The Things They Carried that Martha was never that interested in Jimmy, but she continues to write him letters; he also continues to hold out hope that they will have a relationship. Thinking about Martha provides Jimmy with a distraction from the harsh reality of war; he enjoys indulging in his fantasies of Martha until one of his men, Ted Lavender, is suddenly killed while walking back to camp.

After Ted's death, Jimmy feels like he has been distracted from his duties to his men and vows to be a better, and sterner, leader. Part of this transformation involves his separation from Martha, meaning his decision to stop obsessing over her. His symbolic gestures of burning her letters and disposing of the pebble she gave him represent his newfound devotion to his men and to his leadership position.

The death of Ted Lavender has a profound impact on Lieutenant Jimmy Cross. As was mentioned in the previous post, Jimmy Cross carried a pebble in his mouth as a good-luck token. The lucky pebble provided Cross with feelings of comfort and optimism. Along with the pebble Cross carried photographs and letters from Martha, a girl he was interested in before leaving for Vietnam. These tokens allow Jimmy Cross to forget about the dangerous environment as he daydreams about Martha and life in America while he is on missions in the jungle. After Lavender is killed, Cross blames himself and believes that daydreaming about Martha has compromised his ability to focus on the task at hand, which is to protect his troops in the jungles of Vietnam. Lieutenant Cross ends up burning Martha's photographs and letters, and he throws away his good-luck penny.

Symbolically, Cross throwing away his good-luck penny represents acceptance of the reality of war. The good-luck penny helped Cross cope with the dangerous, stressful environment. Getting rid of the penny illustrates the harsh reality of combat and separation from Cross's idyllic past. No matter how much Cross attempts to repress his discomforting thoughts, he is unable to completely remove himself from the war. Soldiers will never find true comfort in the middle of Vietnam, and daydreaming is dangerous while on patrol. When Cross throws the penny away, he attempts to separate himself from his past. He decides to repress his memories of Martha and feelings of comfort. Jimmy Cross accepts the reality of his situation and vows to completely focus on protecting his troops.

Cross received the pebble from Martha, his girlfriend back home, but as his time in Viet Nam continues, be begins to realize that she really didn't love him, that she was only a fantasy he entertained.  After he participates in the atrocities of war--killing an entire village and seeing men he loved die--he realizes he can no longer carry fantasies with him. As a result, he burns Martha's pictures and her letters and throws the pebble away. His guilt is enormous and he thinks he deserves nothing good, and the reality he has experienced has been so harsh, he can no longer entertain sweet thoughts, hopes for the future.