There are some restrictions on foods - coming back into the US. Basically, anything fruit or vegitable that doesn't look like it was natively grown in Canada is not allowed. See:
http://tinyurl.com/5w2eot
I travelled with the TM through Canada last year - it was quite easy to get into and out of Canada. Going into Canada, they worry about guns. Coming into the US, they worry about food. I will refrain from the obvious political statements I could make.