The boys have been collecting rocks for over a year now. They would dig them up from our last years' winter rental house and then since we have moved here they have been mining at least once a week.
They had really wanted a display case for Christmas. One morning a light bulb went off in my head and I said they each could have a sewing cabinet for their rocks. We cleaned them up, reinforced the bottom of one(thanks Grampy) and lined them with felt(thanks Grammy).
The boys washed all their rocks and spent an afternoon or two organizing them. They are sorted by color and kind of rock, according to the boys. They are both very proud of their displays.
I am trying to be more thrifty and to look at something and think "What else could I use that for?" This seems to be catching, the boys are coming up with lots of ideas from our cast offs.