Try McDonald's. Schools usually work w/ fast food places and also w/ in the school district such as cleaning the school or helping out wherever they need someone.

Moewing lawns shoveling snow working on a farm

Check with your counselor at school. They should be able to tell you if certain stores in your area are hiring under a school program. Grocery stores higher High School age teens. Not sure about 14 year olds. Usually they babysit or walk the neighborhood dogs, mow lawns, shovel snow.