I agree with Dr. Grace.
But when it comes to food source - definitely the food with the highest amount of iron will be liver and then oysters, organ meats and meat in general.
Animal source iron is the most bioavailable.
Plant source non-heme iron is poorly absorbed because plants contain compounds like phytic acid, oxalates, and certain polyphenols.
There are several ways to enhance iron absorption from your diet:
1. Combine with a source of vitamin C or other acidic ingredients (marinades, tomato sauce, etc)
2. Avoid eating calcium-rich foods at the same time with iron-rich foods since they compete in absorption.
3. Avoid antacids (they compete as well with iron absorption)
4. Consider cooking in cast iron pans, which can "fortify" your food.
While working on the diet part you will still need to discuss with a trained practitioner and find the root cause of your low iron level.