I have cited the Records of the field offices - Bureau of Refugees, Freedmen, and Abandoned Lands in a few of my posts. There are over 450 files of them uploaded at Internet Archive, for several states.
The Freedmen Bureau was established to help people transition from slavery to citizenship in the Civil War era.
These records are being indexed at Family Search and, not quite half way through, they can use more people to help out. If you have a little time each day or week you can volunteer, it doesn't take any special skills - just read over the record and fill in the blanks on the forms given to you.
You can read more about the records and volunteer your time at: