Here’s a really attractively displayed project by H. Mathis:

Using Craigslist, I posed a listing in every state. Each had to be unique. The Craigslist post read that I was working on an art project. (oh man, do people love that) I explained that I created a dirt retrieval system to get the dirt back to me, postage paid. They simply had to go into their backyard, collect it, and throw it in the mail. Due to postage each kit cost me around 10 dollars. I ended up sending out over 100 kits to receive the 52 state total. I unexpectedly learned many many things from this collection. The massive differences in soil from each state, the stories told from each individual sending the dirt in, oh…and the dirt from Hawaii is cursed…

I would have liked to see the state dirt arranged in a topographical representation of the states’ landforms, but maybe that’s asking too much.