These are two examples of wide hairbands made by appropriating hat patterns. The patterns I selected are shell and shell variations with decreases.

I especially like the tapering shape the hairbands (as borrowed from the hats) because this stays better in place around the head without need for ties or elastics.

Get good stretchy dk weight yarn for this, and start with a round smaller by about a half to an inch than the circumference of your head (standard is 22 inches).

Baby camel yarn hairband http://crochetology.net/2012/04/new-hairband-from-hat-pat...

Darker acrylic yarn hairband - http://crochetology.net/2012/04/basic-crochet-wide-hairband/