Historical Background
The National Security State
The Church Committee
Before Snowden: James Bamford's Story

Trouble on the Horizon
The Patriot Act: Wikipedia
Total Information Awareness: Wikipedia
Spying Program Snared U.S. Calls: NY Times
NSA warrantless surveillance controversy: Wikipedia  

Senator Wyden's Warnings
In Speech Wyden Says Official Interpretations of the Patriot Act Must Be Made Public (2011)
Wyden On NSA Domestic Surveillance At Center For American Progress (2013)
Ron Wyden's Warning: America Might Be On Track to Become Surveillance State
With NSA revelations Sen. Ron Wyden's vague privacy warnings at last become clear

From the Press Office of The Guardian US: The NSA Files
Key Exclusives: The Story As It Unfolded

A Survey From The Electronic Frontier Foundation
Timeline of NSA Domestic Spying

The National Security State and The Big Picture
American Coup: How A Terrified Government is Destroying The Constitution
The Fourth Branch: The Rise To Power of the National Security State
The Invisible Government, Revealed: The Intelligence Community is a State Within a State
Entering The Intelligence Labyrinth
Wikiepedia: Special Access Programs