Hi K.! There are a lot of CSA's available in the Twin Cities area. The trick is finding the one that offers what you are looking for. Some have just veggies. Others have fruit, eggs, meat, flowers and more. Prices vary on how far they have to travel, what they offer, how often, how long, etc.
We are going with Harmony Valley this year. www.harmonyvalleyfarm.com We get our first delivery May 3rd, and they have quite a few drop off sites in the northern cities, but I'm not sure if sign-ups are still available...always worth a try! I recommend sharing a box...the portions are huge!
http://www.landstewardshipproject.org/csa.html has a great list of farms in the area as well.
I live in the southern burbs, so I can't help you with co-ops in the northern part of town. Sorry!
Good Luck!