If I’m making a toy that’s not for a baby, I sometimes like to use buttons for eyes. You can use buttons with four holes, like this. . .
. . . but if you sew it on with your threads in an X it can make it look like your softie is dead.
I especially like using 2-hole buttons, because you can use the orientation of the holes to add some expression to the face. These two Blockheads have the holes in their button eyes placed up and down. I think it gives them an open, cheerful look.
Placing the holes sideways made them look kind of sleepy. When I tried out the button eyes on the Snake Charmers (a free sewing pattern), I decided I wanted the sleepy look.
My first thought was to place them up and down, so that the football-shaped divet in the middle of the button would be reptilian-looking. But when I tested them out that way he looked kind of menacing. Sideways (and maybe sleepy?) was much friendlier-looking.
So do use buttons for eyes, but don’t just stitch them on all willy-nilly. Use the button holes as a design element and try out a few different orientations to see what looks best.
If you’re trying to decide between button eyes, safety eyes, felt, eyes, and embroidered eyes, click over to this post for a good overview of your options.