When my children were young, we would do summer cleaning of old school papers from the year. Also read "End of School Year Clean-up: Trash or Treasure?" I set up a file to keep in their desk labeled "Certificates and Awards." The end of year awards usually resulted in something being contributed to that file. Sometimes during the year if they won a contest, the award would go into that file. Over the years we have changed from a file to a binder filled with sheet protectors. See supplies here. We have included important letters, sports achievements, newspaper clippings, and community service logs.
When my oldest child was going to apply for her first job at sixteen, we put together a resume. It included her schools, volunteer experience, clubs and awards. We were able to go through that file and list some awards that stood out. When she was writing her college essay, we went to that file to see trends. She wrote her essays based on these trends. My son recently had to update his resume for a volunteer position. He pulled out the binder and easily updated things we never would have remembered.
You never know what your child will ultimately pursue when they get older. Their interests seem to change so much when they are young. For example, if they apply to a college for a degree in science, you will be glad you kept the school science fair awards to see when their interest began. If your child later pursues journalism, it would be good to have kept the earliest published works, etc. The resume really does begin in grade school.