I wasn't required to get a background check, but maybe things have changed since then.
I also volunteered at the local theatres (plays) in my area, getting props, doing scene changes, helping with hair, etc. That was a lot of fun and I met some great people, plus, I learned a lot about the theatre. It was quite rewarding.
There are lots of places to volunteer, and most places are happy to have the extra help. I think it was ehBeth that said the volunteer coordinator is key - the one place I didn't like was due to that person not being appreciative or accommodating. So... keep looking and you'll find just what you're looking for.