I bought a 21 lb turkey (on special for Thanksgiving), and let it thaw for 2-3 days in the fridge.  Then I got a food-safe 5-gallon bucket from Wal-Mart (in the paint department, has large "Food-Safe" label on it), and brined my turkey for about 12 hours in the recipe found here:

https://www.allrecipes.com/recipe/85839/out-of-this-world-turkey-brine/

Since that website has a delayed popup (that darkens your screen), I'm copying the entire ingredient list here:

2 gallons water
1 ½ cups canning salt
⅓ cup brown sugar
¼ cup Worcestershire sauce
3 tablespoons minced garlic
1 tablespoon ground black pepper

Note that the recipe says "canning salt" but all the reviews confirm that this is very, very wrong.  Use kosher salt instead, or you will end up with a very salty turkey!!

Instructions just say to plop the turkey in it and wait 2 days.  Of course, I did about 12 hours, and that seemed to work just fine.  Brining just doesn't take that much time.  I didn't have fridge space for a 5-gallon bucket, so I put it in my sunroom, and added ice, and checked occasionally to make sure it didn't get into the danger zone.

For cooking, I kind of tried to use this recipe here:

https://howtobbqright.com/2020/11/25/bbq-smoked-turkey-recipe/

I removed the giblets and neck and added fruit, just as it said.  I coated the turkey with peanut oil, and then rubbed it with this seasoning, because I'm lazy, and it's cheap at BJ's: 

https://kinders.com/products/the-blend-seasoning/

I tried to cook it at 300, but my smoker which is awesome at fine adjustments had a bit of trouble with a 21 pound chunk of meat.  So I just blasted it with as much heat as I could get for the first 45 minutes.  The probe gave all kinds of crazy readings, and all they really told me was how close the probe was to the giant chunk of cold meat.  Once I got the probe to stabilize, everything was smooth sailing.  I added cherry chips at the beginning and later (apple would have made more sense but I didn't have it), and other than that, I just did 2 other things:

 * Brushed (basted) with melted butter twice (idea taken from that recipe)
 * Injected breast meat with 50/50 solution of apple juice and apple cider vinegar (I do this nearly every time I smoke, it's just easy and the flavors work with anything)

I meant to brush the turkey with bbq sauce once reaching 155, but pretty much forgot.  When I pulled it off, my trusty kitchen probe said 167.  The probes I used on the smoker gave higher temperatures, so maybe they were placed wrong, or are just beginning to misbehave.

When done, I just shredded all the meat I could get out, and mixed it together (white and dark).  It was delicious!