Moishe's delicious rugelach.
Making a shiva call yesterday reminded me of sitting shiva for my sister in 2002. At one point I remarked to a (non-Jewish) friend that this was the only shiva I'd ever been to where no one brought rugelach. The next day he returned, bearing a giant bag of arugula and an expression of "I love you, El, but I will never understand the Jews."