DIY Stacked Pots : This is a great idea for annuals, herbs, and just about any plant or flower the drapes over the pot. Try using pots that don't exactly match but provide interest. Yard sales are good place to find pots.
What a cute idea. Just turn an appropriately sized cheap plastic pot upside down inside the large- and medium-sized pots and pour soil around them. This creates a platform for the next tier and saves money on potting soil.