In my story, there is a modern-fantasy setting, think magic but with 1990 tech. I know that most living things capable of movement can't subsist off of photosynthetic processes alone,but I don't know much about what in general would be edible to a group of Treants.
The Treants are between 6-8 feet tall.
The Treants have a digestive system similar to a human's, but hardier, as they can eat a broader range of plant matter. Their stomachs can digest "anything" plant based, including other treants.They can digest most plant-like materials,and can consume small amounts of meat,but not certainly more than 100cal/day. They move more slowly than people, being made out of wood. They have lower but sapient levels of intelligence. Their organs are all plant-based,but in general, serve a similar purpose to humans' organs.
They have muscles stronger than most humans' muscles, but are also heavier than the average person and thus move slower.
They, in general,possess a small amount of innate magic that animates their brains and gives them sapience. Some of their species, albeit more rare than humans, possess magic. These spellcasters range in power, mostly stereotypical magical runes and enchantments, etc.
I'll just say that they digest food at the same rate as humans do, and need around 2000 calories per day to function.
Counting small amounts of photosynthesis, what would be their primary food source? I can include magical foods but am also wondering if they can graze or eat things besides human fruits and vegetables as part of their diets.