CQ Researcher provides comprehensive reports on major policy issues. Legislative histories, timelines, and contextual information are included as well as very useful bibliographies. CQ is a great starting place for broader policy issues and sections of the reports will often cover more granular topics.
The Rand Corporation is an independent policy analysis organization. They cover many topics, including education. Their information is reputable and they claim to be unbiased; however, all sources should be critically examined.