The easiest way to do what you're looking for is to go to Bordine's or some other nursery and get a packet of wildflower mix. Sprinkle liberally, tamp down, water and wait; you'll have a nice-looking patch of wildflowers by June. If you want to be more methodical, though, you'll need to do some research.

The first thing I'd do is go look up a few seed companies' Web sites and start reading. Since I'm a fan of heirlooms and lesser-known varieties, my favorites are Renee's Garden, Botanical Interests and Seed Savers Exchange. Your other option is to spend some quality time at your public library and look up books on gardening. Write down the names of plants you're interested in, then hit the nursery.

Based on the conditions you described, you'll be looking for plants that will tolerate shade to part shade, hardy to Zone 4. (Everybody says we're Zone 5 here, but sit through one good April ice-storm and you'll reconsider.)

Another thing to consider is what you want your flowers to do. Do you want perennials or annuals? Are you particularly set on attracting butterflies or birds? Do you want drought-resistant species, or those tolerant of poor soils? Write down your needs and look for flowers that match them.

As a sample, I've included conditions in my own yard and some of the flowers we grow. Hopefully you'll find it useful.

Soil: Base soil is mostly clay and quite alkaline; several years' amending with organic matter and mulching have improved planted areas to heavy topsoil with neutral pH.
Light: Back yard is partial shade to full shade; front yard is full sun.
We wanted: Flowers that could tolerate a variety of conditions. Butterfly and bird attractors a plus.

Plantings:
Agastache/Lavender Hyssop - tolerates poor soil, attracts bees and butterflies
Amaranth, "Love Lies Bleeding"
Asclepias, "Monarch Red" - attracts Monarch butterflies
Bachelor Button, "Black Magic" - tolerates poor soil, attracts butterflies
Coreopsis, "Double Sunburst" - full sun only, attracts butterflies
Heliotrope, "Marine" - tolerates shade, attracts butterflies
Nasturtium, "Whirlybird"
Nigella, "Oxford Blue" - tolerates poor soil
Scabiosa, "Fire King" - attracts butterflies
Stock, "Starlight Scentsation" - attracts butterflies
Sunflower, "Italian White - tolerates poor soil, full sun only, attracts birds
Sunflower, "Evening Sun" - tolerates poor soil, full sun only, attracts birds
Zinnia, "Cut and Come Again"

Again, good luck, and welcome to the group!

The list above includes some very nice perennials but I don't know if they are "wildflowers". A seed company that specializes in native seed mixes should be able to accomodate your needs. Stay away from the "meadow in a can" mixes in the discount stores.

Try this place if you would like to start from seed. The prices can't be beat for the amount of seed you get in each pack. For most types it's about $1.00-$1.25 each and you get at least 5 times the amount in each pack as you would from a store, the service is extremely fast and shipping is reasonable (I actually paid a few cents less than what they paid to mail it!). They give you the zones for all types of seed they carry and lots of other info too.

They also have blends of Wildflower seeds for each zone with a huge coverage rate.

Here is a link that might be useful: Wildseed Farms

The land along the Detroit River was historically a home to Tallgrass Prairie species. Many of these make beautiful garden perennials. Dense Blazing Star, Wild Bergamot, Butterflyweed immediately come to mind. Not to mention you'll be keeping our shrinking natural heritage alive.
For more info check out www.ojibway.ca

Keri,

It depends on what you mean by wild flowers. If you mean native plants, then first you have to prepare the soil, which will take all summer, then plant your seed in November. Here are some sources for native plant seed.

www.prairiemoon.com
www.prairienursery.com

April

If you end up buying one of those mixed wildflower seed packs, try to pay attention to what, exactly, is in the blend (most packs carry a fine-print list somewhere). Those mixes aren't always a low-maintenance proposition. There will often be aggressive plants in there like hesperis/dame's rocket and other things that may outcompete more delicate plants. The person who owned our house before us sprinkled one of those things in a corner, and when we moved in, it resembled a weed patch more than anything else.