The most healthful sources of iron are "greens and beans." That is, green leafy vegetables and anything from the bean group. These foods also bring you calcium and other important minerals. Vegetables, beans and other foods provide all the iron you need. In fact, studies show that vegetarians and vegans tend to get more iron than meat eaters. Vitamin C increases iron absorption. Meanwhile, dairy products reduce iron absorption significantly.
To go into a little more detail, there are actually two forms of iron. Plants have nonheme iron, which is more absorbable when the body is low in iron and less absorbable when the body already has enough iron. This allows the body to regulate its iron balance. On the other hand, meats have heme iron, which barges right into your bloodstream whether you need it or not. The problem is that many people have too much iron stored in their bodies. Excess iron can spark the production of free radicals that accelerate aging, increase the risk of heart disease and cause other problems.
So while it's important to avoid anemia, you also do not want to be iron overloaded. It's probably best to have your hemoglobin on the low end of the normal range. If your energy is good and your hemoglobin and hematocrit are at the low end of normal, that is likely the best place to be.
Having said that, you will want your doctor to review your laboratory results and to track them over time. If your hemoglobin and hematocrit are dropping, that may be a sign of blood loss. That can be from benign causes, such as menstrual flow, but can also reflect more dangerous health issues, such as intestinal bleeding.