In medieval Europe, the dress was considered good luck for other women, a type of fertility charm. After the wedding, single women chased the bride and ripped pieces off her dress, leaving her in tatters. Over the years, wedding dresses became more expensive and it became traditional for women to keep them, either as a memento or to pass on to a daughter for her wedding day.
In order to save her dress, the bride would throw other mementos of the wedding as distractions, including her garter. However, unruly and impatient wedding guests were sometimes known to try to take the garter from the bride while she was still wearing it, so the bouquet was tossed. The wedding bouquet is particularly suited to this use, as flowers symbolize fertility, and as perishable items, they are not something the bride would wish to keep.
Today, the bouquet toss is a fun, but optional tradition. Instead of tossing the bouquet, some brides present it to their mom or grandmother, gift it to the couple who has been married the longest, or simply take it home to enjoy as a centerpiece in their home.