Can I be rehired from a previous employer?

I worked at this company for 3yrs about 7yrs ago from today. I was let go because my scores have gotten low due to being out on maternity leave few months prior. I have since applied and got a call for a phone interview. I was asked if I worked anywhere else longer and I froze and said "no". Should I tell them the truth? I'm afraid they won't rehire me and I know after the background check, they will find out I "have" worked there previously. I desperately need a job and think I am ruined due to the history. I'm going to tell them tomorrow at the testing schedule, I just hope they'll reconsider due to the economy and rehire me.