Perhaps there could be her old Hogwarts textbooks. They might hold some special notes or spells that she had discovered during her time at school.
Another possibility is that it just randomly appears one day. Magic in the Harry Potter world can be unpredictable. One morning, Harry wakes up and there it is at the foot of his bed. Or maybe a magical creature, like a house - elf that knew his mother, decides to bring the trunk to him. The house - elf could have been sworn to secrecy until the right moment when it senses that Harry is ready to discover his mother's secrets.
There could be her personal diaries. Maybe she wrote about her time at Hogwarts, her friendships, and her early days with James Potter.
Finding the trunk may also make Harry more determined. If there are any signs of her fight against the dark forces in the trunk, like a plan she was making or a charm she was developing, it could fuel Harry's own determination to defeat Voldemort and protect the wizarding world.
In the learning trunk, there might be a magical map similar to the Marauder's Map but with more detailed information about the Hogwarts library. It could show hidden sections and the location of books related to specific spells or magical theories. There could also be a set of magical crystals that when held, can transport him into virtual scenarios to practice spells and combat skills in a safe environment.
It could be Hagrid. Hagrid is always looking out for Harry and giving him things. He might come across this special trunk during one of his travels in the Forbidden Forest or in some wizarding market and think it would be perfect for Harry.
There could be some of his parents' old school things like their Hogwarts robes, wands (if they were allowed to keep them), and textbooks. Maybe there are also some love letters between his parents or photos of their time at Hogwarts.
There could be compartments filled with clothes that magically adjust to the wearer's size and the weather. One compartment might hold a set of invisibility cloaks, and another could have a collection of magical maps. Some compartments could be used to store portraits of important wizards and witches that can communicate and give advice.
Well, it could be some magical items like a self - cleaning quill. You know, for Harry to use in his studies at Hogwarts. It might also have a cloak that has some special property, perhaps one that can change colors according to Harry's mood.
The learning trunk might offer him a more personalized learning experience. For example, if he's struggling with a certain spell, the trunk could provide a step - by - step guide or even a magical tutor in the form of a spell - casted projection. Also, it could give him the opportunity to study at his own pace without the distractions of a classroom. He can focus on the areas he's most interested in or needs to improve on, like advanced transfiguration or advanced defense against the dark arts.
Maybe it's filled with old family heirlooms like a dusty photo album with pictures of his ancestors he's never seen before, or some antique magic items that were long forgotten.