Most plants have a very high tolerance for iron in the soil. It's much more likely to be deficient than in excess! It's highly unlikely that the iron content of your soil would be high enough to be toxic to plants. So, you should be able to grow most types of plants.
The shade that you mention will be a greater limiting factor. However, you can find many plants that will grow in the shade. See some of the possibilities by checking shade tolerance in the advanced search option in our plant encyclopedia.