There are two directories containing the example code. The first is the basic directory which contains simple examples highlighting different aspects of ruby code. The second is the advanced directory which contains a few examples of more advanced functionality.
The examples in the basic directory came from Dr. Thomas W Bennet at Mississippi College and are a part of his collection of Lecture examples. All code has been documented to reflect this fact.
The examples in the advanced directory came from the book "Ruby by Example: Concepts and Code" written by Kevin C. Baird. Each example reflects this as well.