[John Wagenseil]

For a dollar or two, at Asian food stores, you can buy a life time supply of model rivets, which can also be used as canon balls for small scale sailing ships, or as river stones for dioramas.

And they are tasty.
A small bag of mustard seeds and of poppy seeds provides a supply of tiny spheroids that can be used as rivet heads, canon balls, stones or ground cover depending on the scale of the model.
After finishing the model, if you have left overs, the poppy seeds can be sprinkled on pastries, and the mustard seeds ground up and added to meat or vegetable dishes.
Dried lentils and other peas (dal) can be used as paving or cobble stones, or cooked with chopped carrots and onions to make a nice side dish.


Also take a look at the pasta at your regular food market. Pasta comes in a variety of interesting structural shapes and is good served with clam and pesto sauce, or butter sauce lightly seasoned with pepper and a little olive oil.