2004 Corolla metallic rattling/clanking noise when bumpy

Recently purchased a used car.  65K miles, mostly city.  I replaced 4x tires
(mechanic), shocks/struts in the front (me), and got an alignment (mechanic).  
That got rid of enough of the tire noise that I could start hearing new noises.  
When I am going 20-40 mhp on city streets and I hit a bump I hear a
clanking sound coming from the front/center/bottom of the car.  I have looked
around and I can't find anything loose down there.  Could this be the motor
mounts?  What should I check for?  Otherwise, the car runs well, though it
feels like it will may need a new clutch within the next 20K miles or so.