This list of resources is from the Environmental Science research guide. Please refer to that guide for a greater breadth of resources on environmental data.
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.
There are numerous key statistical projects in education, but these form a core set of materials.