If you are looking for more open areas like meadows and prairies remnants those can be found as well.
Here in Chicago the Chicago Wilderness group puts out a magazine and have a website to help locate these areas.
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In the shade of several mature trees I like the look of a woodland so nature centers have been helpful in deciding what to plant that would feed the creatures and give that airy cool feeling one gets walking in a woods.BiodiversityBaneberry is a favoriteWintergreenChristmas fernsOsmundo fernmianthemum canadenseNature Center Website
For pictures to get an idea of what I am talking about check out the website for biodiversity on the upper east coast. It shows pictures from a nature center called Cranberry Lake.... in NY state.
Cranberry Lake is a 190-acre nature preserve comprised of forest, wetlands, and a 10-acre lake that was carved by glaciers thousands of years ago. There are three miles of trails, including a loop around the lake, and others that traverse the predominantly northern oak-hickory forest. The area is part of the Kensico Reservoir watershed, which provides drinking water for residents of Westchester County and New York City. The name Cranberry Lake is derived from the growth of wild cranberry, which still exist in various parts of the fen.
On a couple of federal websites I found information about the percentages of various ground covers on wooded sites where studies were taking place. This was interesting as deep woods have very different amount of cover than woodland edge. While being exact is not important having an idea to work with helps.Federal publications
We documented the range of percent cover for dominant ground-cover structural components in burned and unburned habitat (stand ages 7-23 y) occupied by Kirtland?s warblers. The mean percent cover for the dominant ground-cover structural components was
blueberry (Vaccinium angustifolium) (9.5%),
bare ground and litter (5.6%),
sand cherry (Prunus pumila) (3.3%),
sweet fern (Comptonia peregrina)(2.3%)
coarse grass (1.8%)
and bearberry (Arctostaphylos uva-ursai) (1.2%).
Burned sites had significantly more deadwood, sweet fern and lichen/moss cover, while unburned sites had significantly more bare ground and sedge/grass.
Prevalent in the understory were Bebb's willow (Salix bebbiana);
bog birch (Betula pumila) (var.);
red osier dogwood (Comus stolonifera);
and speckled alder (Alnus rugosa).
The other three intensively studied nests were in the fir- spruce-pine habitat.
Ground cover included
blueberry (Vaccinium an- gustifolium);
sourtop blueberry (V. myrtilloides);
arrowwood (Viburnum rafinesquianum);
serviceberry (Amelanchier humilus);
spreading dog bane (Apocynum androseamifolium);
and the common bracken fern (Pteridium aquilinum var. latiusculum).
Dominant shrubs were honeysuckle (Lonicera canadensis),
and wild sasparilla (Aralia nudicaulis).
Black spruce (Picea mariana) were dominant in the bog study areas and ranged from 17- 20 m in height.
Tamaracks were primarily around the edges of the bog.
There are other ways to go about finding out what to plant and you may have a more traditional garden in mind but nature centers are still a good place to start...