Right side, single crochet back loops
This is the Tarnation Oval Rug pattern worked in worsted weight cotton yarn. The only modification is to use 3 strands of yarn held together--same size hook, same number of chains, etc. You'll end up making many more rounds to get the same size rug as you would with tarn.
Using multiple strands of yarn gives you the opportunity to create a really nice ombre effect. This rug was made with Lily Camo Cotton yarn, in a variegated green colorway (Renegade) and a variegated brown colorway (maybe Outback-can't remember). I started with 2 strands of brown +1 strand of green, then moved to 2 green + 1 brown, then on to 3 green, next was 2 green + 1 brown, and finally 3 brown.
It machine-washes and dries like a dream. If any loose ends stick out, just push them through to the underside.
Back side, single crochet, back loops