Where can I find large programs which are using design patterns?

I am looking for large programs (5-10K LOC) which have used a design pattern.

I am mainly looking for programs which have either used the Observer and/or Decorator pattern. I am writing a compiler optimisation for design patterns and need large example programs to work on.

No programmer states "I am using this design pattern" before implementing the design pattern in their program, so I would like to know is there are certain types programs which typically use a design pattern so I can look for these types of programs on GitHub?