Mischa Barton had weed and pills in the car

Evidently those unnamed narcotics were marjuana and prescription pills.  TMZ cracked a source inside the West Hollywood police precinct who spilled the beans.  Their source also says that Barton admitted to smoking weed earlier that day.

Cops pulled Mischa over after they say she was "straddling two lanes of traffic and failed to signal when making a turn."

After being picked up on suspicion of DUI, possession of narcotics and driving on a suspended license... Mischa was booked and released on $10,000 bail.