Child Welfare Information Gateway: provides access to print and electronic publications, websites, databases, and online learning tools for improving child welfare practice, including resources that can be shared with families. You can law related information as well.
Administration for Children & Families (ACF): Under the Department of Health & Human Services (HHS). You can find information on Social Security Act, budget, facts of other related agencies (e.g., Child Care Bureau, Office of Family Assistance, Office of Refugee Resettlement and so forth), and legislative and policy information on a wide range of topics.
American Public Welfare Association: http://www.apha.org/
Center for Budget and Policy Priorities: http://www.cbpp.org/
Campbell Systematic Reviews: https://campbellcollaboration.org/
Electronic Policy Network: http://cpn.org/
League of Women Voters: http://www.lwv.org/
Social Policy: http://www.socialpolicy.org/
Social Security Administration: http://www.ssa.gov/