There is no accredited high school known as "Pennford High School" in any widely recognized accreditation database. Therefore, diplomas from a school with that name are
not likely to be valid for college admission or employment purposes. It's possible it's a fake school, a very small, unaccredited school, or the name is slightly different.
If you have a diploma from a school claiming to be "Pennford High School," you should investigate further to determine its accreditation status. Contacting the school directly (if it still exists) and checking state education department records are good first steps.