Some of my favorite fragrant garden plants are
Star Jasmine (Trachelospermum jasminoides) and
Gardenia (Gardenia jasminoides) I have a little Mock Orange but alas, it is the unscented variety
Scentless Mock Orange (Philadelphus inodorus)
I agree with Tim, the bloom fragrance of
Banana Shrub (Magnolia figo) is amazing but it is considered a tropical plant and would have to be grown as a houseplant for most, unless you live in zone 10 or 11.
The same goes with Hoya plants that someone mentioned earlier. Many of us grow these as houseplants because they will not survive cold winter temperatures for very long. There are many Hoya's with great fragrance. These are a few that have wonderful evening and night time fragrance:
Wax Plant (Hoya australis subsp. tenuipes)
Wax Plant (Hoya lacunosa)
Wax Plant (Hoya obovata)
