American Opossums do not eat ticks. This "fact" has been debunked over an over. That idea came from a flawed study looking at animals for use as ecological pest control. (https://outdoor.wildlifeillinois.org/.../debunking-the...)
What they DO eat is far more interesting:
Stomach content analyses have been conducted on Virginia opossums throughout the United States, generally their diet is composed of 14 to 27% mammal tissues, 10 to 18% fruits, seeds and bulbs, 6 to 11% grasses and leaves, 3 to 13.5% insects, 5.5 to 9% earthworms and 3 to 5% birds. Other food items were found more specific to an animal’s location and included up to 22.5% reptiles and amphibians, 10% gastropods, 9% pet food, 9% garbage and up to 5% carrion. (Christiansen, 2006; Hopkins and Forbes, 1980; McManus, 1974; McRuer and Jones, 2009) (https://animaldiversity.org/accounts/Didelphis_virginiana/)