Herbs For Headaches and Migraines

This is a tough one. Herbal Medicine in general is so complicated. And the reason for this, is that we are all complex individuals who have various different and often conflicting reactions to the same medicine. Also, as we are complex individuals, there is the issue of cause and effect. If you don't know what is causing a symptom then you don't know what to treat it with. 
With headaches, it's a lot like insomnia, in the sense that you are dealing with something that you can't know for sure what is causing it, how someone will react to the various herbs that may or may not help, so in essence, what is going to work. Headaches and migraines can be the result of numerous things, and finding an herb or a combination of herbs that will work for one individual can require some trial and error. 
There are 3 different classes of herbs that can be useful in treating a headache/migraine, and then you have to figure out which ones within those classes will be helpful. There are the basic pain killers, there are anti-tension, relaxants, and there are vasodilators/vasoconstrictors. The vasodilators & vasocontrictors have to do with opening up the veins so that blood can flow more easily, or constricting the flow of blood through the veins by narrowing them. This is an interesting theory of how to treat headaches by controlling the blood flow to the brain, and many headache/migraine treatments employ components that either do one or the other. Some people find vasoconstrictors to help with migraines, and some people find vasodilators to be more useful. Caffeine is a vasoconstrictor, and is used in several mainstream over the counter migraine treatments. 
When you reduce the amount of bloodflow, and therefore oxygen that gets to the brain, it helps to calm some headaches. Other people, who may have a headache as a result of vasoconstriction, would require the opposite to remedy the problem. 
Anxiety, stress, insomnia.. these things i'm sure we can all agree on, can cause headaches. There are herbs called nervines that help with that, and I do think that it makes sense to add at least one to most migraine formulas. Kava Kava, Motherwort, Vervain, Lavender, Chamomile, Hops, Linden, Passionflower are some examples of helpful herbs to curb stress, and just basically calm someone's mind. Some are stronger than others, and depending on how severe the headache and whether or not the person is about to go to sleep, one or more of these herbs would be recommended. 
As far as vasodilators and vasoconstrictors are concerned, there are three that I will mention which are used often for this purpose. Two excellent vasodilators are ginger root and rosemary, and the most commonly used vasoconstrictor used to treat headaches/migraines is peppermint. Many people have been known to have been helped by dabbing a bit of peppermint essential oil on their heads near the most painful area or at the base of the head, however, if a vasoconstrictor is not what you need, ginger or rosemary essential oil are good options. Both peppermint and ginger essential oils are extremely potent, so be very careful about how much you use and I would recommend that you use them diluted in some sort of carrier oil, or put a few drops in hot water and use a washcloth to apply. But drinking them in herb form can be effective as well. Rosemary might sting a bit too if applied directly, but I find it a little less intense than the other two in terms of potential for skin irritation when used alone. 
Then there is the issue of muscle tension, that is a huge cause of headaches. Many of the nervines also act as muscle relaxants. A good one for this is wild lettuce, however due to it's comparison to opiates, it is a hard one to find. California poppy is also worth mentioning.
Then there is the issue of dealing with pain. There are some popular herbs that are often compared to aspirin, as they contain the same active pain killing constituents as aspirin. Some herbs used most commonly for pain are Meadowsweet and White Willow Bark. Then there are the herbs that are just recommended most for headaches or migraines simply because they have a history and track record of helping most with this issue. They include: Jamaican Dogwood, Feverfew and Wood Betony. 
The reason I make the comments in the beginning about it being complicated, is because what works for one person may not work for another, more often with things that affect mood and for medical issues where the cause is uncertain. But what I'd recommend to anyone out there who wants to "go herbal" is not to give up if one thing you try does not have the desired effect. Try something else. And even blends are hard, because you can have a blend of 5 or 6 herbs, for example, and you might have an undesired reaction to only one of them. When I say undesired, I don't mean that you will end up in the ER necessarily, just that it might not produce the outcome you are looking for. For example, in the class of nervines, which are supposed to calm you down, or ease you into sleep, there are a few, like Damiana and Valerian, that do the opposite to me, and absolutely spazz me out. So, after some experimentation, I've settled on the ones that work best for me. My favorite herb for just taking it down a notch is Motherwort. And for sleep, my go-to herbs are Hops, Passionflower and Linden. Also, for example, herbs for depression. People become disillusioned because there is oftentimes one herb that becomes super well known for treating a certain symptom. Like, St John's Wort for depression. And when it doesn't work, people don't always know where else to turn. I'm not saying it won't work for you, but all people are different and have different personalities, brain chemistry and more.. so St John's Wort just might not be the one for you. There are several herbs that can help with depression. Some that are just calming, some that are uplifting, some that help circulation or balance hormones or are nutrient dense. Again, depression can be caused by several different factors. It can even just be a result of a vitamin deficiency. So you might want to try some different options, that's all I'm trying to say!! I can just make recommendations, and then you do the experimenting!