Common Core of Data - This annual source collects data related to public schools and state education. Useful tools include directories for public schools and state education profiles. Individual schools also have profiles with useful data, including teacher to student ratios and number of children who qualify for free or reduced lunch. Note that the data will vary in coverage, but most information is at the state level.
Digest of Education Statistics or Reference Room U.S. Documents Stacks - ED 1.326:year - This annual source compiles education statistics; the amount and variety of data is fairly comprehensive. It is organized into chapters that focuses on particular areas, such as Elementary and Secondary education, and features numerous statistical tables. Note that the data will vary in currency and coverage, but most information is at the national and state level.