valve clatter on cold morning starts
Probably not valve clatter, more likely piston slap unless oil changes have been less than diligent. Change your oil more often and maybe it will go away. If it is piston slap, live with it. The “fix” is to rebuild or replace the engine.
If it is the valves being loud, then I recommend fuel treatments that are specifically formulated to clean them. If it is the engine pistons, then check your oil levels and make sure you are using the correct grade of oil for the engine.
Could also be an exhaust leak where the exhaust manifold bolts up to the head.
How long does this chatter last?