Thomas’ often has spare extra large and jumbo eggs because there is not a great demand for brown eggs. Rather than dispose of the spares, they mix them into the packages with the large eggs, giving the customers a little more than what they are paying for. This is an allowable practice. If you take the smallest brown egg from the package labeled large and compare it to a “large” white egg, they should be the same. It’s also important to note that egg size is determined by ounces, not shell size.