Some of opossums’ favorite foods include:

PLEASE READ THIS!
Achieving good nutrition in the opossum is a difficult and evolving task. This challenging aspect of opossum care is one of the reasons that diets recommended by various groups and individuals can be so diverse, and some so detrimental. The opossum as a biological organism is not forgiving of a poor diet- they WILL get sick, lose mobility, or die if they are fed inappropriately.
The Modified Jurgelski- Don’t Do It.
Various sources have advised to feed what is known as the Modified Jurgelski Diet (90% kitten chow and 10% raw beef liver) to juvenile opossums. It is our experience that this diet, or any diet which includes any meat or protein products except in very restricted amounts, or has an excessive amount of Vitamin A or D, as is found in beef liver, is a dangerous diet for the omnivorous opossum. Even Dr. Jurgelski didn’t believe the diet he developed for laboratory opossums was adequate (references available). It is our hope that the MJD will soon be seen as so outdated that this advisory will become unecessary.
We see many cases of Metabolic Bone Disease (nutritional secondary hyperparathyroidism) in opossums that have been fed poor diets. MBD can progress to cause immobility and death, if not corrected quickly and appropriately! It is not a matter of IF the opossum will become ill, it is a matter of when!
The MJ diet is not the only harmful diet being promoted by various groups and individuals AND websites. These assorted diets may be based on canned cat or dog food, chicken meat, eggs, kitten chow, or include excessive amounts of applesauce, human baby cereals, etc. DO NOT USE THEM!
An important note regarding formulae: We are seeing increasing numbers of cases where infants fed “name brand” formula are resulting in hypocalcemic episodes. Untreated hypocalcemia can quickly result in death in infant opossums! Remember that a photo of opossum on a label does NOT qualify it as a suitable milk replacer.
Current diet information, including the pathogenesis of MBD, is available with membership in the National Opossum Society. It is against N.O.S. policy to publish complete diet plans or infant formulae on its Web site, or to have others publish it electronically. In our experience, it is essential that anyone trying to provide care for any opossum be in telephone or face-to-face contact with an experienced opossum rehabilitator. This is ESPECIALLY true if you are trying to correct MBD. Therefore, we ask that you establish this contact with a call to your local experienced opossum rehabilitators and veterinarians. You will find that the N.O.S. membership packet is filled with valuble information about the welfare of opossums, and phone numbers for experienced rehabilitators.
What Do They Eat in the Wild??
The diet that the National Opossum Society recommends is based on several studies wherein the stomach contents of wild opossums were analyzed. All studies show variation in diet according to season and habitat.
The following table is drawn from one of those studies, published in The Murrelet, Spring 1980, authored by David D. Hopkins and Richard B. Forbes. The study was performed on road-killed opossums in and near Portland, Oregon.