meat and green veggies.
If you can't tolerate veggies, try cooking and pureeing them. Instead of red meat, try veal/calf liver, chicken livers, other poultry meats. Avoid pork. Breads and cereals have added iron, but they are more difficult to digest and also contain phytic acid, which inihibits the absorption of nutrients.
You can also take a dose of liquid iron everyday.
It's hard to keep up iron being a crohnie, so healthy eating and supplements are key. ;-)