Can I Buy Rectangular Tortillas?

Cut the rounded edges off to make them rectangle. When you buy a wrap, it is usually with a round tortilla.

LAVASH!!

It is a soft (tortilla-like) thin bread in a rectangle. You can order it at most mediterranean restaurants, but I have also bought it at walmart - deli section, below the meats, by the hawaiian bread and pita.

It's delicious and very versatile.
Google image search "Lavash rolls" and you can see how well they work as wraps. They are not expensive either - about as much as tortillas.

I have never seen one but I suppose they prob exist somewhere. A quick Google did not turn up much. The FlatOut Wraps are sort of rectangular but they are much more costly than tortillas.

http://www.flatoutbread.com/products/flatout-wraps/