You are growing Centipede, get the poorest soil you can get your hands on with lots of acid in it. Centipede requires very poor and acidic soil to thrive. If you get good soil weeds like Bermuda, Zoysia, and Saint Augustine might pop up and take over :>)

Nevertheless tigerland1 is correct, this should not be labeled topsoil. It's suitable as soil conditioner, or maybe potting mix, but from the description, it's not soil. You should call them and complain. I always advise people to find a torn bag (or accidentally make a finger sized hole if you have to), and get a look at the contents of any bagged product before buying. The cheaper it is, the more important this becomes.

Look at this as a wonderful opportunity. Less organic material for you to find and labor to add for your plants. If I wanted a lawn with the plantings I know how I would go about it. Three to eight inches isn't very much, so it could be all done by hand ... if we're not talking about a ginormous amount of space. First I would get out as many garden hoses as I have and use them to sketch out the wanted lawn area. Doing it this way gives you a good idea of how it will look in real life, as opposed to a pretty drawing on paper. You can leave them there and reconsider after you've lived with the plan a few days. Move as needed. Once your ready to begin, gather up the mulch that's in the future lawn area and use it to create berms in the flower bed areas, keeping in mind these will decrease in height quite a bit over the next year. But with luck you will still have enough added height to add drama to the floral scene. IF the flowers are to be viewed from both sides , the height needs to be in the center of the beds, with tallest plants in the middle. I did this a couple times with a picket fence at the front of the house and the extra height of those taller plants on the small berm not only helped give more privacy to the front yard and front windows, but the street view was much more eye catching. Everything just looked so much bigger than expected. I'm not talking about a high berm, just enough. ;) Vary the heights of the raised areas too or the whole thing gets too predictable. If by chance you find old dead, thatch where a lawn used to be, and it doesn't seem suitable to be planting on top of , this too can be used for added flower bed height. Just clear a space, throw all that thatch can be used, then cover with more of the compost material. Regular shrubs and perennials can work their way through that sort of thing just fine over the next year or so it takes to break down. I have routinely planted directly in mushroom compost that comes from big trucks ( the bagged is finer) and never had any problems. But that doesn't mean yours isn't slightly different, plus your different climate. What about watering an area and then checking later to see how well it holds moisture ? Heck, throw a test plant in there while your at it and see what happens to it. Hopefully you will not need to spend $$ on more soil to maintain a moisture level. Better to spend on plants and cool hardscaping! Oh, and the perfect birdbath.:) Now get out your collection of garden books and magazines and have fun looking at all the beautiful designs you admired in the past. You have a wonderful, fertile blank slate to work with. How exciting.

Gem-Dirt will deliver by the dump truck load. Last fall I bought a dump truck load of pure leaf compost. It looked wonderful at the time and as a soil conditioner I think it was great. It's not nearly as good as what I consider "compost" which is what comes out of my compost pile. I've used two-thirds of it and what's left is now greyish and the rain has washed it down so that there are all these tiny rocks on the surface of it. I planted some watermelons in it thinking that I'd get some use out of the pile but they aren't growing very well. That makes me very suspect of it. A melon should go NUTS to be planted in pure compost. These seem unthrilled to be there. So if someone offered it to me for free I'd take it as a soil conditioner, because my soil is so lousy, but I wouldn't pay for it again. Gem Dirt delivered to Skiatook for an extra $30 (for the dump truck). They also offer top soil and a mix of top soil and leaf compost they call rich mix. If you're new to the area, I'll also give a plug for the Tulsa Greenwaste site which is also on the north side of town and free, though they don't deliver as far as I know. You can get all the wood chip mulch you want there. While it's a bit rough, it is free and mostly devoid of trash.