Magpies have a strong bill with a sharp cutting edge, which can be used for cutting flesh, digging up invertebrates, or picking fruit. Their main diet in summer is grassland invertebrates, such as beetles, flies, caterpillars, spiders, worms and leatherjackets.
In winter, they eat more plant material, such as wild fruits, berries and grains, with household scraps and food scavenged from bird tables or chicken runs, petfoods etc. They will eat carrion at all times and catch small mammals and birds.
Don’t judge. Being of the species Pica Pica, the Magpie will eat most anything in a pinch, though she’s partial to russian tea cakes. However, it seems humans have equally wide ranging tastes, from pancakes to spicy fish, porridge, mango, and fermented cabbage. See the whole multi-national smörgåsbord: