There are also limited PDF reports at Maine Education Policy Research Institute on K-12 education and at the US Regional Education Laboratory / Northeast and Islands program, with studies on e.g. rural schools in Maine. For full data, you would need to contact project authors.
National sources for education data include:
Child Trends DataBank has summary charts and reports on child welfare, well-being, demographics, development, education, and health.
International sources for education data include:
The NCES International Comparisons in Education includes statistical data for cross-national comparisons of education indicators and assessments from Canada, several European countries, Japan, and Russia.
OECD Education Statistics include excel charts of attainment and expenditures as well as math/science performance, by country.
UNESCO-United Nations has detailed education data in customized tables.