Sneak down the hill to the south where you'll find the bobblehead on a small table. You'll find the Perception bobblehead on a shelf. The Museum of Dave is one of the few buildings you can go into without first talking to Dave. If Megaton has been blown up, then you can't get the Strength bobblehead. Complete the Power of Atom quest and get yourself a house in the town, then you can get into Lucas' house without picking the lock.
