I can't remember which was firstbut there are 2 I remember from being reali young like 4 and 5. My mom dressed me up as a bag of M & M's. She took a black trash bag, cut a whole for my arms and head, wrote the letters M&M on it, and then put little colored dots all over my face and arms.
The other one I was a chocolate chip cookie. She took 2 pieces of cardboard and made a circular sandwich board and drew on the chocolate chips.
I love the simple costumes, even now.