Yeah mowing does suck. Here check this out.

Here is a link that might be useful: Prairie Moon Nursery

I would reccomend you do some reading on both the prairie moon nursery site and on the www.prairienursery.com site.

Both sites have good information about preparing field such as yours for a wildflower planting. One key note is that I would not just buy a bag of wildflower mix at the local big box retail store. These mixes tend to not be successful for many years. You want a quality seed mix from one of the websites mentioned previously or from a local native plant supplier check, with Indiana Native Plant society for recommendations in your area.

You do want to mix grasses with your flowers. If you do some reading you will figure that out.

what is the history of your 2 acre field of grass? Would it be possible to stimulate a dormant seed bank of wildflowers with a prescribed burn, where you may not have to plant anything? Or has it been plowed and planted as a farm in the past?