Organic edible flowers and other garnishes
I have needed to find this sort of stuff as well - its not easy to find sometimes!!
Uncle George's Place downstairs (across from Stonemill) at the St Lawrence Market can carry them but you do need to preorder. The number for them is 416-601-2112. I believe that in the past I have gotten both pansies and nastusium flowers from him. Also, since he specializes in organic foods I am relatively certan that they would be organic as well. I also know that he carries all kind of other sprouts etc (including popcorn shoots) so you might be able to get other kinds of garnishes from him.
I don't know if they were organic or not, but I picked up some organic flowers from the Harvest Wagon on Yonge a few weeks ago. They had a few varieties of flowers in, but I'm not sure about 'other garnishes'.
As for garnishing/carving tools, you might try one of the kitchen supply stores on Spadina in Chinatown.
Hope this helps,