The National Institutes of Health, Office of Extramural Research, has provided resources on sample grant applications:

“If you are new to writing grant applications, sometimes seeing how someone else has presented their idea can help as you are developing your own application. With the gracious permission of successful investigators, the National Institute of Allergy and Infectious Diseases (NIAID) makes available examples of funded R01, R03, R15, R21, SBIR/STTR, K, and F applications, summary statements, sharing plans, leadership plans, and more.”