How did Midge, the miller's son, outsmart Robin and his three yeomen?

Midge drew the men to a sack of meal at the table, and when he had them close enough..... he blinded them by throwing it in their eyes.

Then slowly the Miller arose to his feet, and slowly and unwillingly he untied the mouth of the bag, and slowly thrust his hands into the meal and began fumbling about with his arms buried to the elbows in the barley flour. The others gathered round him, their heads together, looking and wondering what he would bring forth.

So they stood, all with their heads close together gazing down into the sack. But while he pretended to be searching for the money, the Miller gathered two great handfuls of meal. "Ha," quoth he, "here they are, the beauties." Then, as the others leaned still more forward to see what he had, he suddenly cast the meal into their faces, filling their eyes and noses and mouths with the flour, blinding and half choking them. Arthur a Bland was worse off than any, for his mouth was open, agape with wonder of what was to come, so that a great cloud of flour flew down his throat, setting him a-coughing till he could scarcely stand.