1) Either the cone or funnel through which grain passed onto the grindstones, or a basket, especially one used for sowing seed.
It has two meanings and the distinction is not always obvious. In documents which have to do with corn mills it referred to the cone or funnel through which grain passed onto the grindstones: 1572 the hoppers and the troughs and all other things concerning … mens corn and meal, Doncaster
1607-8 the milne arkes, hopper, pickes, Shepley
1656 roapes and pulleyes, hopper and mill Arke, Eshton
1758-62 make itt like a mill hoper, Wakefield. It could also be a basket, especially the one used in the sowing of seed, and here again the context is important: 1423 2 panyers, 1 hopir, 1 modius, 1 firthindal, Beverley
1577 iiij scottels, a hopper, a maunde, North Frodingham
1619 Sede corne, first wett it, then throwe it in unslecked lyme, turne it and tosse it therin, then sow it fourth of the hopper, Brandsby
1619 two buckets, bols, dishes, maunds, scotls, one hopper, pigons, cannes, Bingley.