Courtesy of Brenda S., Thompson Street Farm, Glastonbury CT
I use the # 10 size Pac Sell bag, which is big enough to hold 1 lb. of greens, which is the quantity I sell  to my restaurant client.  For the farmers market , I use the same #10 bag, but only put 4 oz. of greens in them. Last year I put 5 oz. of greens in the bags, but people complained 5 oz. was too much to eat in a week.