I have done this lesson in the past, and every year my students LOVE it. This project is a lot of fun, and is also a wonderful way to get rid of some of the "junk" we as art teachers hang on too. It is also a great lesson to teach about reusing and recycling. Quite a long time ago, I found this lesson on Kids Artists, I enjoy this lesson every time I do it.
For this project we used; old pieces of cardboard for the bun, scraps of yarn and felt, old noodles (that have been the the cabinet for years), and leftover Easter grass. I also let my students use my scrap paper box to cut out any shapes they wished to add to their sandwich.
The results are wonderful! It makes me hungry just looking at them.