While parents can upload documents directly to MyFiles, attachments that were uploaded with a message, a journal entry such as a Check-in or Moment, or an expense entry will also be documented within MyFiles as well. 

You can see which files in your MyFiles list are attachments to messages, journals, and expenses by clicking the 3 dots to the far right of each file row in your list. If a file is an attachment to another entry, you will be presented with the option to view the entry in question or download the file attached to the entry.