My dentist says you can't have a gold crown atop a tooth which has a silver filling since it creates a magnetic pull?

Magnet, no: Galvanic action, possibly. There would be two dissimilar metals contacting each other, and with the salts in your saliva, you can have an exchange of ions, like a battery. Have your dentist explain this to you further and your treatment options.

Galvanic shock: Gives a sharp and jolting feeling due to electric current caused by these metals.

Trust your DDS: Gold crowns, on top of amalgam, create a permanent galvanic cell and compromise the outcome.