For your research project, you may use government documents. Some of them are peer-reviewed, and some are not, but a great deal of research is published by the U.S. and other nations. U.S. government websites come in all flavors. Some are meant for the general public, some for children in grade school, and some are technical. Technical reports include more detail than a typical journal article.
Federal government departments and agencies, as well as state agencies, provide many of their unclassified publications freely via websites and report servers. Examples from the U.S. federal government include those maintained by the U.S. Environmental Protection Agency, NASA, the National Oceanic and Atmospheric Administration (NOAA), and the Department of Energy.
There is an overall search of most of them at: Science.gov and Statistical Abstracts of the United States will be useful as well.
Government info is a rich source but the websites can be quite confusing. Please let us help you when you have questions!
If you are looking for info on writing a report or citing sources (creating a bibliography), see the Find Articles tab!