Passport and you are in. On the food front it is not as bad as a few have stated. Do check as sometimes if there is an outbreak they will not allow certain things.
Right now bird flu has been going around so chickens have been on a list last I looked.
Beef is generally ok just keep in the store packaging. Again could change if a few mad cows turn up.
Some fruits and veggies are ok and some not. In the west we have bugs and diseases they don't want crossing the border so many that are grown both sides are not allowed so for those things just to buy when you get there.
Dog food is ok as long as it is in the original store packaging and has no lamb in it. Most don't realize it is the lamb that they are really looking for not the dog food itself. We even have our dogs on the raw diest and take a week or 2 with us and no issues. You can also take any dog food if it originates from the U.S. Just make sure it is unopened original store packaging and clearly marked made in the USA.
Saying all that do check in case something breaks out and things change. Some items are cheaper stateside too so better to just buy there and not worry. I do enjoy my Alberta beef steak when we go to Montana or Washington. Yum.