What can visitors bring to inmates?

I'm going into Lynwood on Friday, for felony DUI charges. This is my first time being in trouble, let alone going to jail. My friends want to know what they can bring to me while I'm in there. I shouldn't be in there too long, but can they bring me books? snacks? I'm not really sure what the guidelines are like for LA county jails. Anyone know what they're allowed to bring me? Also, I got sentenced to 90 days....how long do you think I'll actually serve? Any information would be appreciated. Thanks, ~Laur