The best place I know to start looking for patterns is www.ravelry.com. It’s free to join. Knowing your approximate gauge with your yarn would be helpful. You can search for vest patterns and specify a yarn weight, look at the gauge needed for various weights of yarn, and determine which one yours matches. Here’s a search for men’s vests there. http://www.ravelry.com/patterns/search#craft=knitting&availability=free&pc=vest&view=captioned_thumbs&sort=popularity&fit=adult%2Bmale