Amerson played high school football at Samuel F.B. Morse High School in San Diego, California, from which he graduated in 1993. During his sophomore year, his team (the 1990 Morse Tigers) was voted by the San Diego Union-Tribune as the best football team in the history of San Diego County. Amerson's high school teammates included former NFL players Tommy Bennett and Rashard Cook, former University of Arizona players Gary and Cary Taylor, former UCLA player Teddy Lawrence, and former Navy players LeBron Butts and Gervy Alota. Amerson won the Walter Payton Award, given to the most outstanding NCAA Division FCS (formerly I-AA) offensive player, as a senior at Northern Arizona University in 1996.
