|What plants within the U.S. can you eat the roots, stems, leaves, flowers, fruit, and seeds?|
|Do you mean, what can you eat, as in what won't make you sick, or do you mean, what entire plants are commonly eaten? I can't think of a single plant that is commonly consumed in its entirety. But take, for example, dandelions: you can eat the roots, leaves, and flowers, (and even make wine). I don't know of anyone eating those fluffy seed pods, but hey, who knows?
Radishes are another plant where you can eat the roots and leaves. And some radishes are bred for their edible seed pods.
I guess that's the key here. Plants have been bred for specific characteristics. For example, some radish varieties have been bred for their succulent roots, other radish varieties for their seed pods (these may have bitter, but still edible,roots).
Echinacea (Purple Coneflower) is another plant that comes to mind. Herbalists use the entire plant--roots, leaves, and flowers, to make a medicinal tea or tincture. Now, I've never heard of anyone eating the entire plant, just making an extract from it.
Onions and garlic are another family where roots, leaves, and flowers are eaten.
I hope this is helpful to you. There are probably thousands of plants that you could eat in their entirety and suffer no ill effects--but I can't think of any that are commonly used in that way.