My neighbor, while spreading a thick layer of tobacco stems across his pasture (I have no idea what for), got quite a few into my garden. I tried to remove it, but somehow a good amount has been chopped up with the soil this spring. Will that harm any of my vegetables?
Perhaps he's aiming for organic matter / compost in his pasture? Seems like a good way to encourage stray deer to keep coming back! ;)
I don't know, but I doubt that your veg will take up any significant quantities of nicotine. A quick search didn't turn up any useful information about uptake by plants.
The main harm that comes to mind is the possible transmission of tobacco mosaic virus to your Solanaceaa (tomatoes, potatoes, pepper, eggplant).
Also, if there is any significant quantity of nicotine related to the stems in your garden, it could be harmful to your population of beneficial organisms.