Hi Kayleigh,
" I'd like to try to breed very very similar to the Dreamland zinnias, without them being F1, but instead an open pollinated source. "
One direct way to do that would be to grow some of your favorite Dreamland zinnias, and then save a lot of seeds from them. The Dreamlands probably are F1 hybrids, so your F2 seedlings will vary quite a lot, but some of them will resemble the parents. If you grow quite a few of them, you might even get some that you like better than the original parents.
By growing a lot of seedlings and culling heavilly to keep only very-good-or-better specimens, you could very well improve the breed, particularly if you repeat that for more than a year. A lot of my breeding has benefited from lucky mutations, but some of my breeding has been just repeated selection for the desired trait. For example, a few years ago I noticed some of my Whirligig zinnias had irregularities on their petal ends that reminded me of "teeth". So I intercrossed those specimens and began selecting only those that showed toothy characteristics. By saving seeds from the "toothiest" specimens each year, I was able to accentuate the characteristic to get a unique look in zinnia blooms.
The toothy look combines well with two-colored petals.
By saving and growing an excessive number of seeds from your Dreamlands, you could be very picky about which ones you keep and which ones you cull and remove. I know in advance that I am going to cull my zinnias heavily, so I plant them closer together to compensate for that. At first bloom I remove a lot of plants that don't further my breeding objectives.
You could do the same thing. And you could actually make improvements to the commercial Dreamlands. For example, both Dreamland and Magellan don't have a really great white, so they refer to what they do have as "Ivory"
http://www.hazzardsgreenhouse....
You could be very picky about which white ones you saved seeds from, using only the very whitest. And if you reallyl wanted to make some quick progress in that direction, you could grow some of Burpee's White Wedding zinnias, and cross them with your Dreamland Ivory specimens.
http://www.burpee.com/flowers/...
You also might find yourself with somewhat different preferences in the plant forms from what Dreamlands have, so you could select for plants that meet your preferences.
Another thing. When you are growing your Dreamlands with the intent of saving seeds from them, you might notice that some specimens aren't putting out much, if any pollen. Don't hesitate to take some pollen from Dreamlands that are producing pollen and apply it to the "shy ones" that aren't. As I like to say, "Be the Bee". You can do a much better job of pollinating your zinnias than the bees do. Bees aren't trying to pollinate, they are just gathering zinnia nectar, and any pollination they do is purely accidental. By doing deliberate pollination, you can increase your seed yield many times over what the bees might give you.
ZM
