That first one looks like Indian Grass. The yellowish green one might be switchgrass? The last two pictures look like little bluestem, the few remaining seedheads look like it along with the stems. If the stems are very flattened where they come out of the ground, its little bluestem.

Hey Cactus, Thank you! You nailed the second one! I googled it and sure enough.. Schizachyrium scoparium

Actually, the first five pictures are all the same species - the weird color change is because the first pic was outside in the light - the wind was blowing so hard I couldn't get the camera to focus because of the movement so I took the remainder of the shots inside... I googled both Indian Grass and Switch Grass and I'm still not sure.

Well, it reminds me I need to go back to this place I visited with my shovel and some pots before winter sets in. I dug one up that was a lot smaller than that first one you have there, as I only had a hand trowel on me and it was stiff like that with blue blades which really stood out as BLUE and it was Indian Grass, I finally figured. The seedheads are long and vertical with orange seeds that are fairly big and there is a leaf thing wrapped really tightly around it and it sort of comes out of there gradually.

I found a virgin field that is full of little bluestem, big bluestem and sideoats grama and some unknown others by a church and they gave me permission to come out there. There is one type I can't figure out that is a clumping type, about a foot and a half, with curved sort of wide leaves (about 1/4") and it has stiff seed heads that are skinny. Its driving me bats trying to ID it. I thought maybe Eastern Gamma grass? There was no switchgrass. I see that more in areas where the land has been overgrazed or disturbed.

The native switch grass has been blooming for quite some time now here with the seed heads way up high and is rather rough looking. I don't think yours is switchgrass. But maybe I am mistaken about this grass, I just think of it as switchgrass. When you see it here, it dominates and aggressively takes over an area and looks weedy. Its kind of yellow green and I definitely wouldn't want it in my garden.

I went out and dug up some various types of native grasses today. I got two large Indian Grass clumps and I found out how you can tell if thats what you have, which I am pretty sure it is. Where the leaf attaches to the stem, look to see if its pointed and when you pull it away if there is a sort of notch like a gun sight, If it is, its Indian Grass. The leaf starts out narrow and sort of pointed and then gets wide and then ends in a sharp point. I found a picture of this on line but I don't know how to attach a photo here. The ones I dug were dormant looking, completely dried up and had very stiff stems with seed heads, but the one I already had is still green/blue since its been watered. We are so dry here this fall in Oklahoma. You said yours was growing in wet clay. These were in very dry pure red clay but they still dug up pretty easily. Looks like it spreads from underground roots but I read its not really aggressive and they separated very easy.