They make Cedar planks out of WESTERN cedar for smoking Salmon and vegetables. The EASTERN cedar is the one that is toxic, so I would buy the planks packaged in the grocery store to make sure it is safe other than going to the lumber yard and getting cedar not knowing where it came from.
Both cedars can be used for grilling, red cedar is used more because the modern version of plank grilling of fish is a west coast idea originally and red cedar predominates there. Red cedar is usually preferred for cedar chests because of its pesticide like qualities that ward off insects and the fact that it prevents mold and fungus growth, this would seem to indicate that red cedar has more of those oils that create that distinctive cedar smell and taste than white cedar.
3 sites that sell white cedar planks-