If you want to grow a citrus plant, I suggest you start with a seed from fruit either bought at the store or pilfered from a wedge from your glass of water at your favorite restaurant.
If you look at the seed itself you probably won't be able to tell what it came from. I currently have this very problem.
You see, what happened is this. I get the seeds out of many different citrus plants and figure that one day I will finally plant them. I don't know how long you can save a seed before you plant it, but I'm pretty sure it's at least a few months. So, some of the seeds I still have might never be able to grow.
The next few pictures are of some of my seeds. In the first picture all the seeds are mixed up because I haven't bothered keeping them straight. The second picture is the same as the first but I decided to use a flash. The third picture is my valiant attempt at separating the Meyer lemon seeds from the rest of them.
I'm pretty sure I got those right since I didn't rinse those off as well as some of the other seeds I have saved so there is a darker yellow color to them from the lemon itself. The other seeds were scrubbed well and have almost no coloring to them apart from the husk of the seed and insides.
Citrus has to be one of my favorite things to grow since I have had so much success with starting from seeds and the seeds are so easy to get.
For more citrus information see my Citraphile Blog.