best non-recruited walk on ever: Pete Sherry.
http://www.mensracing.com/news/2004/petesherry.html
Sherry walked on to Gagliano's team in 1986, ignorant of the fact that many of his teammates were national-class runners on full scholarships. Sherry had only started running a year and a half earlier, after he was cut from the varsity soccer team at Horace Greeley High School in Chappaqua, New York.
"He came in as a walk on — I think as a former baseball player in high school, and his classmates were some of the best runners in the country," said Gagliano.
But having grown up playing sports since he was a 5-year-old, Sherry wanted to stay involved with a team atmosphere and get faster. "Being naïve helped a lot," he said. After a rather dismal freshman season, Sherry dedicated himself to running.
Five All-American certificates and a leg on Georgetown's championship 4 x 1,500 meter relay at the prestigious Penn Relays in 1991 resulted from that simple-minded dedication.
"He had and still has a tremendous drive to succeed," said Gagliano. "He was a loyal person to his institution and his teammates and really wanted to contribute, just a great team player."