There are a few options.
1) Traditional engraving. This is done with a rotary cutting tool, not a laser engraver. It produces a scribed etched surface.
2) Laser engraving on a coated metal. A laser burns the coating off, revealing the metal underneath. This is what most laser shops do now.
3) Laser marking. A chemical is applied to the bare metal and then heat-bonded with the laser. Not as many places do this, as the chemical is expensive and falls under haz-mat regulations.
4) Actual laser engraving. This is rare. Most trophy shops don't have the kind of laser it takes to directly engrave metals.
5) Other processes, such as printing
I recommend you find a local trophy shop to work with. They'll explain what they can do, and usually don't charge much for plates.
Regards,
Eric