Over the centuries, envelopes have contained many secrets and declarations of true love, so it's appropriate to use a group of them to store dear old letters and treasured notes -- or to fill them with trinkets for your valentine. Just stick several envelopes together, using their own adhesive; then insert your keepsakes, and tie the bundle with the most beautiful ribbon you can find.
First, fold the flaps back on all but one of the envelopes you want to join. With the unfolded flap on the bottom, stack the envelopes, open side up. Moisten folded flaps; affix each to the envelope behind it. Punch a hole through the bottom center of all the envelopes; insert keepsakes, and fold last flap over. Thread a ribbon through the hole, and tie.