There are so many plants that will make your yard a fragrant garden. In our yard we have the two very fragrant shrubs, that you are probably tired of hearing me talk about, but they are the Osmanthus or Tea Olive and the Sweet Almond. They are evergreen....which means they have leaves year round and they have flowers year round.
Little Gem is a magnolia which has blooms off and on throughout the year but mostly in the spring and into early summer. It's name Little Gem is a perfect name for it....it's a tough tree, has leaves year round and keeps to itself in your yard. Flowers are large, white and very fragrant.
Gardenias are very fragrant. Beautiful white flowers that really smell nice. There are many to choose from.....take a little whiff.....then take it home. Just make sure you get one that's been grafted.
You can't miss with a Rose or two......Perfume Delight is a favorite of ours and it's well named as it's scent is just like a rose should be.. It a beautiful medium pink. We've had ours for quite a few years.....it still looks great. Roses need full sun. Yearly pruning will be needed.....best time to do it is in mid February.
Loquat is an evergreen tree and when it blooms in the spring ...it's small clusters of flowers will give your yard a very nice scent......and what follows will be a clusters of fruit that are absolutely delicious.
For vines.....there's Honeysuckle, Confederate Jasmine and Moonflower. They smell very nice and would make interesting additions planted by a fence or trellis.
For annuals try Dianthus, Petunias, Stock, Scented Geraniums, Nasturtiums or Sweet Alyssum.
Many Orchids can have very nice scents....some even smell like chocolate.