Grave yard dirt is a wonderfully potent magical tool that has a plethora of uses. It can be used for most any undertaking, and all that is required is a little forethought and caution.
Grave dirt can be literally bought, but I do not recommend this. I suggest a method alternate to the above called 'buying' it. Now what's the difference and why one over the other you might ask? Well 'buying' the dirt requires no middleman and is you going and getting it yourself, from a graveyard. Now before we move any further, know that the collection of said dirt is illegal in some areas and I am not promoting the theft or help in stealing from the private property of any graveyard. Now back to the topic at hand, 'buying' allows you to be a little more sure on the source, and as to whether it was taken or 'bought' by the gatherer (A very important side note in all this is that even if the gatherer has 'bought' the dirt, it was given to him/her not you, so it will be regular dirt for you). Never just take the dirt, it is rude and can have negative consequences, besides the dirt won't do anything then(I'll explain why in a little).
Now the origin of the dirt is especially important. Why? Because who is beneath that dirt affects the uses of the dirt itself. Now on to why who was beneath dirt is important and how it affects that dirt's uses. The person's spirit (or if you don't believe in spirits their energy) leeches into the dirt they are surrounded by. This, if you believe in spirits, creates a connection to the spirit of the deceased and allows them to help you. Now, for all the people who opt out on the people spirit thing, you can see it as energy and knowledge being utilized from the dirt, but I'm not going to go through the whole thing splitting up these two the entire time. If you really want that then ask afterwards and I'll do an additional piece in this post. Now there is a direct correlation between the person's life and what they did and what the dirt is good for. (Ex. A doctor would be helpful in healing, a solider in guarding, a criminal in most ill-intentioned magics). Know also that taking from the grave of someone you don't know is risky and should be avoided, generally. Taking from someone you know is much more effective. You can always do some research and find out about the unknown person, but as stated previously I don't recommend it. On a side-note soldiers are particularly good for the purposes of graveyard dirt due to their obedience in life, but once again make sure you know who you are asking and an idea of what they were like. Some people also like using spirits of young children, I would never do that, but that's completely up to you.
Now for collecting dirt. Since it is illegal I won't give you a method to do so, but rather tell you a story, and if you get it good. If not, whatever. ''Little Sally, a young and studying witch, once wanted to help her grandma get better because she had been sick. She looked for many methods of doing so and stumbled upon a spell needing graveyard dirt. She did some research and learned how to collect it. She decided to go to her great-grandpa's grave because he was a doctor. She knew you weren't supposed to take dirt from a graveyard so she bought some flowers and a vase, put dimes in the bottom, added water, and put the flowers in the vase. She went down to the the cemetery and asked her great-granddad's spirit for his help with grandma, and upon feeling his consent, she took the flowers from the vase, dumped it out leaving the dimes as recompense, and took some dirt, just a handful or two, no more. She went home and did said spell and grandma got better.'' I hope you got the process. Though if you are more familiar with the spirit then you can personalize the offering, such as I'd bring my dad, were he dead, a vodka with red bull. Also, let me emphasize that little Sally didn't bring a bucket and take a bucket of dirt. Moderation. One more thing, as for just taking it, never do this! You are using a spirit to help you, and in stealing from them, you do not make them more amiable toward you or your goal.
Now, we have the dirt. Where do we keep it? How do we keep it? How long is it good for? Good questions. I suggest a place away from small children and one that is dry. As for storage, the container should be marked with what the dirt would be good for and who gave it to you. Timing, now here is a good question. Personally, I'd keep it at most a full lunar cycle and afterwards, if I haven't used it, I return it and ask for more, if you need it, with another payment.
I add a note to all this that normal spirit work precautions should be taken when dealing with spirits. Be respectful and well-mannered. Do not try and force anything and should you feel the dirt giving off negative vibes return it.
Please feel free to post any questions or comments :D
-http://paganwiccan.about.com/gi/o.htm?zi=1/XJ& ; ;zTi=1&sdn=paganwiccan&cdn=religion&tm =11&f=00&su=p284.13.342.ip_&tt=11& bt=3&bts=32&zu=http%3A//www.luckymojo.com/ graveyarddirt.html
-Thanks to Moegami for reading over it and fixing any errors she found
-Thanks to ConjureLady for legal loop holes