The main goal for most of the areas I've worked on is to provide optimal nutrition for the deer and turkey. Doing this will also take care of lots of other species of wildlife.
Basically deer need a high protein diet spring and summer and a high carbohydrate diet fall and winter. Clovers, alfalfa provide good spring nutrition. Later soybeans add another high protein option that is very popular with deer. Early fall I plant winter wheat which will stay green late in the fall and provide a green food sorce early in the spring. It is a great cover crop when doing fall establishment of legumes. Corn and soybeans are tough to beat for fall/winter, carbohydrate sorces in Iowa. The colder the winter the more wildlife will need them. Ideally they will last through February and March into the green up of spring food sources.
For our feathered friends I'd add sorgum. It works great for pheasant, quail, turkey and songbirds.
I also agree with AJ, check with your local DNR biologist for help. These people are trained to work with wildlife and can provide valuable input.
Also contact your local county Pheasants Forever chapter. These are hard working people trying to raise money to help wildlife and wildlife habitat in their county. They may be able to provide free seed for your food plots. They are also great to work with on other aspects of habitat developement including establishing switch grass and tree and shrub plantings.
If you are like me, in the long run, you will find that planting food plots, developing habitat and getting new people into hunting are just as much fun or even more fun than the hunt itself. Good luck, get out there and have some fun!