Good photo, but there are many bamboo that look like that. It's almost surely a Phyllostachys, but I can't tell the species. In any case, if you can post with closeup shots of the culms (like 2' away) to show any distinguishing characteristics (e.g., nodes, striping, etc.) it would help. Also, what part of the country are you in?

You can cut down the culms for poles any time; new ones will grow (though not from exactly the same spot), generally in the spring. Since you have a running bamboo and the grove is pretty good size, you will need to put in some maintenance work to keep it from spreading where you don't want it. Cutting down the poles does nothing to prevent the roots (rhizomes) from spreading underground, so you will have to chop down into the ground all around the grove in late summer to sever any wandering rhizomes. They're usually within a foot of the surface. As long as they haven't established themselves, severing them will kill anything past the cut point and you don't have to remove it. You could put bamboo barrier down, but that would be a big job involving digging a ditch about 30" deep and placing a special high-density roll plastic in the ground and backfilling. I've included a link to a web site where you can look at pictures of bamboo that are typically grown in the U.S.; as you will see, there are many Phyllostachys species...

Here is a link that might be useful: Bambooweb

Thank you so much kudzu9 for the help. I took a couple of close up pictures as you suggested. I hope this isn't too close. If so, I'll repost another try.

The foliage:
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The base of one of the many plants:
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Again, thank you so much for the tips. A friend is asking for a few plants, so this is good timing actually.

Good picture. In fact, that makes ID easy. The compressed nodes at the base are characteristic of Ph. aurea, a common, but pretty bamboo. It's sometimes known as "Fishing Pole bamboo" because the compressed nodes make for a good handgrip. There are several varieties of Ph. aurea (such as Ph. aurea 'Flavescens Inversa,' which has a yellow colored sulcus), but I suspect yours is the standard Ph. aurea.

Thanks so much kudzu9!!! Yay, I have a name for them now. :D

If you don't mind, I'd like to ask one more thing. I mentioned a friend who is interested in some of my plants. Do you have any suggestions on digging them up, so they do not become stressed? Or are they so hardy that it likely won't affect them?

Any tips are greatly appreciated.

magnoliasouth-
You can dig out some of them for her, but it will be hard work. Also, to best insure success, you will want to wait until the bamboo are more dormant...I usually make divisions of bamboo plants in February or March before the spring-summer shooting season starts.

I will email you some digging instructions using your GardenWeb email link. If you don't get something from me today, please re-post here so I know and we can figure out another option. (My experience with GardenWeb email is that sometimes it works great, and other times things just disappear and never arrive.)