Civiced.org, focused on the U.S. Constitution and Citizenship, offers a good amount of info and meta-info related to these topics. Several speeches and papers are available, while a lessons plan is organized for different ages and school levels.
The Center for Civic Education is a nonprofit educational corporation dedicated to fostering the development of informed, responsible participation in civic life. Content is produced by the center staff under a grant from the U.S. Department of Education
Contents, lessons and documents are available as weblinks descriptions or pdf material. Papers, text-books and speeches are included in a clear metainfo structure and often downloadable
A good amount of papers, speeches and lessons is available. Some pdf documents are comprehensive, while other resources (such individual lessons) provide just some meta-info
Civiced.org is focused on the U.S. Constitution and citizenship. Also speeches, documents and general contents are focused on topics strongly related to PS studies
Resources, news and courses are generally updated every month