They would have tossed into the dump pile anything that no longer had value to them that could not be gotten rid of by burning (in fireplace or kitchen stove) or composted (organic leftovers from the kitchen). So some scrap metal is undoubtedly in the dump. And that metal is most likely ferric (iron) like cans & broken irreparable tools. Whereas anything of copper, tin, pewter etc. would have had potential value to the 19th century homesteading farmer. This later case suggests that running your metal detector around & over the footprints of former barns & out-buildings might produce as much diggable treasure as dump piles (because 19th century barns were the repository for all the farmer's castoff but maybe usable scraps). Though the ground is frozen right now, I don't know any reason why scanning with a metal detector in Winter won't be as productive in locating prospective digs as in Summer; Winter might actually provide you the advantage of your being able to get through brush that will not be as easily accessible in Summer. But don't rush the poking & probing with a shovel until after it warms up enough & dries out enough that you can comfortably sit on your identified spot and carefully push back the top couple inches of duff/turf to a distance of an arm's length all around using hand tools like a small trowel and a short pointed wooden stake. After you have some idea of whether you have located a whole vein of dump pickings or only a single old nail, then you can decide whether to turn over whole shovel-fulls, or try "sounding" by working a 3' iron pin into the ground until you "feel" something hard, or continue to sit there, working over the surface with just the trowel & "dibble". Go slowly & carefully or you will surely break something you would rather not have. -BobB