I'm going to the states on Sunday and planning on doing some shopping at wal-mart and target. I was wondering, in the US are you allowed to use more than 1 coupon on a product?

in canada we can't stack coupons, but I heard that it can be an option in the US. Should I know a secret couponning trip while I'm there?

I'm actually going to print out coupons here and bring them with me. I'm using the walmart and target coupon portails as well as coupons.com should i be checking elsewhere?