Google Drive has a handy "Shared with me" tab for finding the documents you have access to, but don't own. However, there are also several hidden search operators to help you narrow down your documents by collaborator. As tips site Make Use Of points out, you can use the owner: search operator to find Drive documents based on the name or email address of the person who owns a document. You can also use the to: operator to filter documents based on the person you've shared a document with.
How to Search Google Drive Documents by Collaborator [Make Use Of]