These resources collect and disseminate huge collections of education-related data, produced by the United States federal government, other agencies, and associations in the field.
Sometimes, contacting NCES staff is the only way to get started on finding the right data, and they are generally very receptive to requests. Here is a list of all NCES staff and their contact info.
Open Doors, supported by a grant from the Bureau of Educational and Cultural Affairs at the U.S. Department of State, is a comprehensive information resource on international students and scholars studying or teaching at higher education institutions in the United States, and U.S. students studying abroad for academic credit at their home colleges or universities.
There are numerous key statistical projects in education, but these form a core set of materials.