I had to eat the apple I was carrying before I was allowed in.

I saw a documentary once about US Customs and Agriculture. They were standing in the airport with a dog who was specifically trained to smell out sausage, among other agricultural products, to prevent foreign crop related diseases from comming into the country. I don't remember why sausage was so bad though. I'm sure if you met that lady and that dog, they wouldn't have let you take your flour with you.