You are probably getting more of these nutrients than your report shows. Niether of the nutrients mentioned is mandated to be listed on a food label, so if a member is using the nutrition label to input data, the amounts will not be available---even though the food may be a good source.
For food sources of potassium and magnesium, click this link. Select "nutrient lists", then select the nutrient you want by amount. You will get an extensive listing of foods. Hope this helps. ndb.nal.usda.gov/
SP Registered Dietitian