Congressional Research Service (CRS) Reports are non-partisan policy reports written for the use of Congress. They are a great way to get background on both foreign and domestic policy issues.
The Public Papers of the Presidents have been published for every president since Herbert Hoover in 1929. The volumes contain a compilation of speeches, press conferences, public messages, etc. Executive orders and proclamations were not regularly included until 1977 (beginning with the Jimmy Carter administration), the sources below include an archive of these documents.
Foreign Relations of the United States (FRUS) contains important diplomatic and intelligence communications between U.S. officials and between the U.S. and other countries. It is considered the official record of major U.S. foreign policy decisions, but are generally published about 30-35 years after events because of the sensitive nature of the documents included. FRUS volumes currently cover 1861-1980.
Google is great, but it includes EVERYTHING. Try the search engines below to search only for government information.
Before you start your research choose a citation manager that works best for you! It will help you keep citations to all your articles, sources and data in one place making things much easier when it's time to write your papers. EndNote Desktop software is available for free through ITS, and the more streamlined EndNote Basic is available for free on the web.
Take a look at these related research guides for additional resources and information.