I’ve mentioned the daily document feed from the National Archives in the past. The daily feed is a way for US History teachers to collect primary documents they can use in their lesson plans. Our Documents.gov is built from primary documents in the National Archives collection. One of the good, free offerings from Our Documents is the Our Documents Teacher Source Book. This free 76 page document is available for download. The book contains many primary documents as well as ideas for teaching with those documents. The book includes lesson plans and handouts that you can reproduce. The documents in the Our Documents Teacher Source Book cover events from 1776 through the end of the 20th Century. Download the book here. You may also be interested in the Our Documents list of 100 Milestone Documents.