Hi ya'll,
This is my first post on seeking some landscaping advice.
Here's my story...
We just moved into this house a few months ago. The backyard had your typical patio slab coming off the house, with a small piece off land/grass separating it from the fence. In my opinion this was wasted space, so I wanted to create something pleasing and give us more room to use. The area of grass was roughly 5'x15', and by the look of the grass, it looked like the previous owner had a dog because the corner was dug up and some very large rocks was put in place. My first thought was to dig up the grass and remove the dirt and start fresh, but this is Texas, the ground is very hard and I was working alone. So scratch that idea. I got a suggestion from a guy at Home Depot to lay clear plastic over the grass so the heat would essentially kill it, and I wouldn't have to worry about digging and finding somewhere to put all that dirt. So after a few weeks in the hot Texas sun, the grass died and I was ready to work on the area. I left the plastic down on the ground as a "weed" barrier and started to fill in the space with river rocks. I then laid 2x2 pavers down over the rocks. After I got the pavers in the right position, I glued travertine tiles to the top of the pavers. Finally I sprayed the river rocks with some water sealer to get a nice "wet" shine on them.

Now, we've been noticing a strange smell in this area. Almost a kind of rotten smell. Some days it's stronger than others. It's hard to pin point where it's coming from. Could this be from the clear plastic underneath the rocks? Is it rotting and giving off this smell? If so, how can I get rid of it, without having to dig up 300+ lbs of rock.
OR is it from water not being able to drain properly into the ground?

Any advice?

Thanks,
Derek