My super duper easy Knit mary janes (all done in stockinette).
There is hardly even a pattern to these:
if you say 5 stitchs is an inch, cast on 30 stitches, then go until you reach from your heal to the tip of your biggest toe. These dont fold over, see the sides are sewn so no need to knit any longer than the actual size of your foot.
Then knit 2 together for 2 rows, and cast off then sew em up! (found this one on craftster.org)
the strap is sewn on so the button is just for looks, no button whole needed. Sew up the sides as far down as you want them to be, then add a strap, or not depending on how you like it. I did mine in stockinette but they can be done in any stitch really mine are 3 stitches wide.
I made some for my fiance, but forgetting the stap and adding in a square of ribbing which made them wider and more manly (though not a lot).
We are going to take them to a shoe shop and have them add a sole as well so they can be worn even outside.