If you've graduated with a BFA in one major does that mean you can go back and get your masters degree in a completely different major or does your masters have to consist of the same field?

Well you don't necessarily have to get your masters in the same feild of study that you got you bachelor. However there may be some pre reqs that you have to take. For example you could have graduated with a BS in Biology and then get your master's in Early Childhood Education. You may still have to take some undergraduate classes and tests but it can be done. I hope this ans your questions but if you have more questions why don't you go to a university's home page and ask someone in their graduate department.