You may be interested in several tabs on this Social Work Research Guide. The Alumni Resources tab has a list of free policy databases. Also within the Alumni Resources tab is a section for free electronic books. Several of the electronic books focus on government /policy information. The Reference tab on this Research Guide has a subpage with free statistical resources. Some of the free datasets may also be of interest.
Several Research Guides may be of interest:
Social Policy-Brown School Library
Washington University Elections Research Guide
Washington University Geographic Information Systems (GIS) Research Guide
Washington University Government Research Guide
Washington University Political Science Research Guide