Looking for stones

I've taken up an interest in fengshui recently and one school of thought calls for the placing of a flat rounded stone about the size of two fists at the "base" of my home.

I would imagine something similar to the stone labs people use for "paving" a path in their garden will do the trick. Except smaller.

This might mean that a trip to the garden store would yield my answer but I'm generally too busy to go and my patience is thin when it comes to looking for things, especially if I have run around town to go to different types of stores and then walk up and down various aisles or wait eternity for someone to help me at each store.

So hopefully one of you can point me in the right direction. Again I'm looking for a flat rounded stone about the size of two fists.

大圓石春