Are you referring to Union soldiers taking home black slaves they had emancipated? If so, I have come across quite a few instances where this was done. Offers were made, but not always accepted. If there was not a huge black exodus North immediately after the war, perhaps it was due in no small part to a goal of many slaves, to search for their families from whom they were separated when they were sold.
Here are a couple of examples-
Oh what a feeling of manhood came to me with those words. I felt myself a man, every inch of me. It was my second taste for freedom, the hiring for wages being the first. I took the revolver and cartriges and made up my mind to follow directions if I should be molested and that I would deserve my freedom. I remained with Captain Smith till his term had expired. He and many of his regiment re-enlisted, they were given a furlough and I accompanied him home to Detroit.
Source:
William Jackson came home with me as he desired. First I found employment for him as a waiter in a hotel and next in the service of a railroad company. He needed no more help. His sterling qualities won success. For twelve years he served as a station baggage master in our city. He then started in business for himself,
Source:
Service With the Sixth Wisconsin Volunteers by Rufus R. Dawes