Hi Elroy,
To migrate Public Folders from Exchange Server 2007, please make sure it has been updated to Exchange 2007 SP3 RU10 or later. And to start the migration process, please follow the steps in this TechNet article. The migration scripts can be downloaded in this article which are used to Export the on-premise Public Folders and import the contents into the Office 365 Public Folders.
If you have any concerns when migrating the Public Folders, please feel free to post them in the forum. It is our pleasure to be of assistance.
Best Regards,
Bruce Zhou