Well popps I wanted to push hard enough to get a harrow before responding, but am about to say the hell with this, so I figured I'd provide what I have experienced. I have 172 feathers, but lost track of actual maps along the way. No more than 10% of the feathers came from deceased birds, so lets say I've done around 155 maps. From these, I obtained 0 harrows, 3 nests, and 10 stuffings (all from nest bags, none from inside cornucopias). I've also gotten 8 plucked birds, none of which came from a nest bag directly. I have 63 cornucopias, somewhere between 25 and 30% of which have popped directly into my backpack (playing with 1720 luck, I'm not sure if it played a factor or not). So 45-50ish of the cornucopias likely came from nest bags. If my results are a "true" indication of spawn probability, which may or may not be the case, figure no more than a 1% chance of a harrow, about a 2% chance of a nest, a little higher for a stuffing ("maybe higher;" from other posts nests and stuffing %s may be the same), and around 33% for a cornucopia. We all are suspicious of the RNG, moreso after Draconi let the cat out of the bag that dev had determined something wrong with it, so it's hard to say if I'm simply unlucky or if this is par for the course.
I don't want to rant/ whine/ complain, but I do feel like dev missed the ball on this one, particularly frustrating following a very well done Halloween event. In the former, you could accurately forcast effort to desired result, and it played well. The Thanksgiving event, while an innovative and enjoyable process (up to a point), relied on luck on the RNG, again the latter of which is known to be flawed. IMO, whoever decided to put a 1% on anything, considering the RNG, erred in judgement. I know I'm frustrated and now borderline irritated, and doubt I'm alone.
Hope that helps and sorry for being so late.