Under "My Items" you will find any item that you have added to the shopping list. These come from the quick add widgets on the dashboard and on the shopping list page. Any item you like can be added to this list for easier shopping.
The grocery list shows all the items you need for your weekly meal plans by category. You can click the box next to any item to indicate that you already have that item and do not need to purchase it. All items are categorized for ease of shopping.
When creating or reviewing your shopping list, use the quick add to add any other items you would like to add to your shopping list. Many people use this to add snacks, drinks, and household items that may not be part of the meal plan.