Django: how to create a unique instance of one model as a field in another model

I am trying to store an instance of an items model as a field in my users model using ForeignKey like so:

class UserProfile(models.Model):    user = models.OneToOneField(User, on_delete=models.CASCADE)    username = models.CharField(max_length=255)    items = models.ForeignKey('Item', on_delete=models.CASCADE)    def __str__(self):        return self.usernameclass Item(models.Model):    stats = models.JSONField(null=True)    name = models.CharField(max_length=255)    def __str__(self):        return self.name

However, it currently seems that every new user is sharing the same list of items when I check my Django admin panel (essentially, there currently exists only one Items instance that is shared by every user). Instead, my goal is to have each user have their own list of items, unrelated to other users' list. Is there a way to make each user have a field in their account that is a unique instance of the Items model?