If it's an apple, it's edible? Best to stick to regular apples. Mayapples are edible when fully ripe. Until then they will definitely make you sick. On the other hand, they were much used historically as medicine. Maybe we kids were right, and medicine IS bad stuff.
This view of young mayapple plants, growing with wild leeks, was an earlier trip to the Preserve. Mayapples spread by roots, so this may be all one plant. The darker leaves are mayapples.