Our Native Plants and Ecosystem Services is a great place to start when choosing plants.  You can filter by soil moisture, light, bloom period, etc.  

https://www.canr.msu.edu/nativeplants/index then click on Plant Selection then Plant Search tool. 

I'm reluctant to name specific plants because you will need to consider mature size, bloom time, and light requirements.  The website will help you narrow down your choices. 

Native plant nurseries are also good sources of information.  Purchasing locally is preferred over mail order catalogs or the big box stores.  

As for finding volunteers, the Extension Master Gardeners provide education, they do not plant gardens or maintain them.  Sometimes garden maintenance is part of the education, but it is not the purpose of the program.  You could consider posting flyers asking for volunteers at the library or recreation center. You could contact local landscape compaines and ask if they offer discounted rates for the type of project you are doing.  https://www.mnla.org/ You do not need to be a member.  Click on the box Homeowners Enter Here, then enter the zip code. A list of landscaping companies will appear.  

I hope this helps, it sounds like a wonderful project!