Answer: Unfortunately Burpee does not offer these two plants. Gas plant (Dictamnus) is a specialty perennial available by seed and occasionally as plants. In my experience it can be very difficult to get started either way, but once established is long lived and very easy to grow. Sneezeweed is sometimes used to describe Achillea ptarmica and sometimes for Helenium, two very different plants. These are also perennials and also available as both seed and plant. Since this is your front yard and since perennials can really take two years to hit their stride, you would probably be happier purchasing plants.
Rather than making suggestions without knowing the growing conditions or your color preferences, please allow me to refer you to an excellent book, The Heirloom Garden: Selecting and Growing Over 300 Old-Fashioned Ornamentals by JoAnn Gardner (Storey Communications) ISBN 0-88266-751-3. You will find many of the plants/seeds in this book are offered by Burpee. Another highly informative specialty catalog, Select Seeds Antique Flowers http://www.selectseeds.com/index.htm includes both seeds and plants in a wide variety that would be appropriate for your garden. Good luck with your project!
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