I have found dried roses, lavender, and violets available for purchase
online at Kalyx.com <http://www.kalyx.com>. Their products come from
Frontier Natural Products Co-op and the Co-op's quality control
information (including details about their organic certification) are
available on the site at http://www.kalyx.com/catalog/aboutherbs.htm .
Otherwise, I found them dried at Stony Mountain Botanicals
<http://www.wildroots.com/>, but there was no stated policy about
organic certification. On both sites, dried violet leaf was available
but not dried violet petals, but all the tea recipes I've seen have
called for violet leaves rather than petals, so that may not be a
problem for you. Otherwise, I have not seen any source for dried
violet petals that were preserved in such a way that they would be
safe for eating.
You mention that you would like to use the dried petals in jams and
jellies, but I've also noticed that most of the flower jam recipes I
have seen use fresh petals rather than dried. You may already have a
recipe for preserves in mind, but in case you do not, I'll also
include a few recipes for jams using fresh blossoms and sources for
buying fresh edible flowers:
Rose Petal Jam
Lavender Jelly at Seasoned Cooking
Tomato-Lavender Jam at RecipeSource
Violet Jam at Epicurious
Violet Jelly by Karen Garner
Edible fresh flowers are available for purchase at these sites:
Finding the fresh edible flowers was relatively simple, but finding
them dried and still edible was more difficult. I only found the
Kalyx site when I began searching by individual flower type, so if you
need other kinds of flowers for teas etc., that's the way I'd suggest
beginning your search.
I hope that helps you and you enjoy many a pleasant cup of tea!