Excessive plate waste is generated in elementary school cafeterias. Adapting nutrition promotion strategies to target waste reduction and encouraging mindful and sustainable eating (MSE) are possible strategies to encourage students to reduce waste during school lunch. "Farm to Tray, Tray to Farm" is a 16-week intervention that aims to encourage elementary school students to develop mindful and sustainable eating behaviors. An educational curriculum was delivered to eight 5th-grade students, who served as peer leaders and disseminated messages throughout the school. Additional strategies included cafeteria reinforcements and opportunities for food recovery. A pilot test of the program was conducted in two schools using a quasi-experimental design. A pre/post survey was administered to 3rd-5th-grade students to measure changes in MSE behaviors, and analyses were conducted using the test of marginal homogeneity and t-test for independent samples to evaluate within- and between-group differences, respectively. In total, 169 students (n = 102 intervention and n = 67 comparison) completed both surveys. From baseline to follow-up, intervention students reported significantly increased self-efficacy to base lunch choices on body cues. A higher proportion of intervention than comparison students increased ratings regarding behavioral strategies to practice MSE and expectations of benefits from MSE.