An heirloom brooch, earring or other keepsake can be either integrated into the bouquet or added to the handle.
Besides jewelry, just about any object can be incorporated into flowers for your wedding. The main factors to consider : scale of the item to the size of the flowers/flower arrangement, the weight of the object (if applicable), and the delicacy of the item (antique brooch, heirloom of substantial value, etc) and how effectively it will be incorporated into the arrangement. I personally have incorporated many objects into bouquets and boutonnieres, each item was personal to the bride, groom or both. Remember the item needs to reflect something of you or the groom, an interest or hobby can even be represented by a simple fly fishing lure. Talk to your wedding florist about what custom touches you can bring to the flowers to make your wedding day a little more unique and personal.