We have been, kind of, amateur breeding lots of our seeds. The bees do most of the work. We interplant varieties some too.
(This is a nice article about horizontal breeding that I am very interested in for localized seeds. http://newfarm.rodaleinstitute.org/international/pan-am_don/nov04/chapingo.shtml
We did our garden last year mainly just for fresh seed for our seedbank. All the food was gravy... There was plenty to put away and give away. Almost too much to handle. Our seed bank is overflowing. Our cupboards are full'o jars. With a little work you can have fresh greens, but we take a break in the winter and eat a lot of sprouts. If you are in Missoula area, there is a nice winter market. Check out the thread in the Missoula forum at permies.com.
As far as MT, we are in the bitterroot at about 3400'. we're on a south facing hill and so our ground thaws earlier than the neighbors. But then down only about 300' elevation (3 miles by road), in the river bottom, they get "spring" nearly 3 weeks earlier. So it all depends on where you are. And how well your system is set up to grow.
The farmers markets are a good way to get starts or locate local seed possibilities.
Basically here, June is safe to plant your warm crops (some of the worst ice storms ive seen were in june - july). Your nightshades and many warmcrops will likely need a good headstart indoors. Unless you have some serious thermal-mass (like a rock) and a pond or something, its going to be difficult to get nice fruit on your nightshades and peppers without some type of coldframe/indoor scenario during the early spring. We start many things in cold frames. I even cheat with warmer pads on certain things. In the fall, we cover our more vulnerable plants during frosts. If you can raise your beds atleast 2', you will get a longer season on each side, but then, 24" is a lot of work unless you are doing a small jigamaju.
(Some of these permaculture characters can supposedly grow citrus outside
up here... so ive heard! )
So the season is farely short here, but with good timing, a good system and a little research, you can grow almost anything. If your soil is happy and you have some sun and water, should be good. Just watch out for the deer. If you don't have a dog or something, think about fence. (I've heard that human urine works well keepin'em at bay. Sure and fine to share the foods, but if the deer get it before there is fruit...)
I would recommend planting garlics and marigolds and clovers and companion plantings, and all such. We recommend perennials and are getting various berries and fruit/nut trees in here as fast as we can.
As far as veg goes, don't forget: rotation, rotation, rotation, etc.. If each year you improve your soil, as opposed to damaging it, you can't go wrong. (Here is a glimpse of Missoula area ideas... http://www.youtube.com/watch?v=_IMLCFrzpTk
What types of things are you looking for? we might have what you need. Or our neighbors might. Depends on what you need. Hope your garden went well last year! Spring will be here again soon, good luck!