I would like to plant some shrubs that would provide an assortment of colours and textures in my Christmas wreath. Any suggestions?
What do you mean by Christmas wreath? You can look at any of the Dogwoods, which will still be attractive in the winter once they've lost their leaves. Also, Heliotropes, which are a lovely deep purple and smell terrific. Unfortunately Lantana is invasive in your area; it's also lovely. Perhaps Hibiscus syriacus (Rose of Sharon) trimmed to meet the height standard? Or Lilacs (Syringia) or Rhododendrons or the list is kind of endless.
I make a wreath at Christmas was various greens - I learned how to make them at the UBC Botanical gardens. So the trees/shrubs need to be evergreen.
Ok then. Thuja occidentalis has neat berries and an interesting texture; Hydrangeas give neat variety with broadleaf; and I'm really fond of the cones of larch or tamarack for wreath although the trees themselves are deciduous. Pines are lovely, and if you can get Casuarina to grow then it's got very unique evergreen foliage and "cones" as well. You can also look at using grapevine as a base and then interweaving the needle-foliaged branches into it, along with some Ilex (invasive, be careful) and of course Eucalyptus, especially the young leaves, is very decorative. That might have to be an indoor plant, though.
I see true firs, hollies, false cypresses and true cypresses used here - look at web sites of suppliers to see what they are using. Often there is some kind of cone or berry included in addition to similarly resilient foliages. Just searching "wreath making" might turn up quite a few good ideas.