Cattledogs are a thing, not for defense of the herd particularly but for moving a herd even short distances they provide a huge benefit and the longer you have to move your cow the more useful they get.
I was unaware of that, thank you.
Okay, depending on the time period we're talking for the interchange, changes what the Norse have to offer in the first place, and I think we need to cover that. Are we talking the height of Norse settlement? Then we have about a thirty year span in the twelve hundreds where thay'll have cows, sheep, goats, and horses, by the late twelve hundreds they had lost most or all of their cattle, they never had large amounts of horses, and bones in their middens, combined with isotopes in their own bones, find they were surviving almost entirely off of goat, sheep, and seafood by later periods. As far as I have read, their sagas never make mention of them having brought dogs, though they may have considered it unimportant, and I haven't found any source mentioning the discovery of dog bones near their settlements, though, again, they may have considered it unimportant. Now, population estimates vary, but the range, at it's height is generally held to be between 2000-10000, recent work preferring the lower end, now, I tend to take population estimates with a heaping grain of salt(looking at
you hundred million people in NA guess...), but I'm usually willing to accept a number within a range provided, so I'd put their population at the height of settlement at about 4000, based on the number of confirmed houses, 625, and guesses at the average household side. That, plus a couple hundred in Vinland, is a very low population, compared to Iceland, which at the time had approximately the population it does now, with nearly a millenium of agricultural advances, to me meaning they would've been unlikely to trade or gift them. You want a really in-depth discussion of this, check out Lands of Ice and Mice, by DirtieCommie(hope I spelled that right) and DValdron. In historical situations, you'd need a reason for all the Greenlanders to pick up and move to Vinland, then slowly get assimilated by the natives who would completely, massively, out number them. Maybe the king of Norway being a complete imbecile before Greenland was completely dependent on trade with Europe for its survival, and passing his law requiring trade to come directly through Norway, rather than being allowed to stop off at Iceland. During hood weather, a trip to Iceland and back was a few weeks, an equivalent trip to Norway was a few months round trip at best, and with no chance to make effective repairs on the way if neccessary. If a king passed that law, say, a century earlier, when trips to Vinland were still being made, and Greenland still supported trees, I could see the abandoned Greenlanders pulling up their roots and heading, quite literally, to greener pastures, especially if they had less aggressive contact with the native Americans.
The plow won't be adopted in the same ways I also want to say that without the earthworms that changed the soil ecosystem of North America forever those grains from the old world just won't work outside of alluvial soils.
Corn is calorically the superior crop with a better input output ratio.
You're ignoring one minor detail here, as I have mentioned before, corn likely hadn't reached this far yet except as a trade good. People were eating corn, but until about the 12-1300s, they weren't growing it yet, certainly not as far north as the Norse would be having contact with them.