Sentimental gifts for a boyfriend express your love and devotion to him. These gifts are often handmade, but you can also buy a meaningful gift and customize it for him. Find out what he likes. If he appreciates photography or loves taking pictures of you, make him a scrapbook. Or you could buy him something to wear on a daily basis so he is always reminded of you.
Buy your boyfriend a custom watch that suits his tastes. Have the watch engraved with a sentimental message from you. Avoid saying something too simple. Instead say something about why you are within him. You can say something like "I love your eyes, I love your smile, but most of all I love you." You can also include a nickname that only you know on the watch. For instance, you could say "I love you, my Iron Man." Try to say something that truly expresses how you feel about him. You can tell him you love him, but spice it up by adding his nickname or a longer, more sentimental message.
Gather all the pictures of you and your boyfriend together. Create a scrapbook highlighting these pictures and place the oldest pictures on the first few pages. Scrapbooks are progressive timelines that catalog events in order. The book is a representation of your time together and he may notice how your relationship has evolved as he flips through the pages. Choose plain or patterned card stock that compliments the photos and decorate each page with embellishments. Place tickets to your first movie together or other sentimental items in the book.
Write your boyfriend a romantic letter and roll the piece of paper into a small scroll. Buy a clear or cobalt blue bottle with a cork and slip your message inside. Cook a romantic meal for him such as roast quail or one of his favorite dishes. Place flowers on the table and put the message in a bottle next to the flowers. Proceed with dinner and see how much time passes until he notices the bottle. He might notice it right away, or he might not realize the bottle is for him until later.