Help, Help!!

A company is doing background check on me. I didn't tell them I have an unrelated degree.(I didn't put it in the resume), I'm afraid they will be able to check it out.
Is it possible they can get all the degrees I have earned (in USA)even if I don't tell them? They go to individual school to check? Or there is a database which contains all people's education info in USA?
It has taken me a very , very long time to get so far in the job search journey, I don't want to lose it.