When we visit Grandma and Grandpa Miyasaki in the desert, we fossil hunt, and collect all sorts of fun sandstone pavers, little rocks, BIG rocks, white rocks, black rocks, Jasper, Petrified Wood, Rose Quartz, plenty of sandstone, etc.
So, it's just a natural reaction for the girls to be in HEAVEN when they discovered our zeriscaped yard (an area completely covered in ROCKS) in Arizona. There are ALL kinds of "pretty" rocks in our yard, and they have their own little rock collection area on the side of our house. It looks a lot like a quarry. They've separated their rocks to size, type, color, etc. We even spray painted some of them blue...
We love rocks, as long as they stay out of our heads!