What about Bergenia? That has nice round, glossy leaves and blooms in spring time. I think there are some hostas that do well in full sun but I think they still need moist soil.

Syreeta

Here is a link that might be useful: {{gwi:753860}}

Cannas and Ornamental Rhubarb come to mind. Castor Bean plants. How much room do you have?

Hollyhocks

I am thinking lower plants than than the ones that have been mentioned. But thanks everyone for the input

Oh well then what about
- geraniums &/or pelargoniums
- lamb's ears (stachys)
- columbine
- nasturtiums
- red salvia
- dusty miller
- shasta daisies and gaillardias don't really have round leaves but they are broader.

Hope that helps!

Another idea that isn't big leaved - I like to soften using Gypsophila (Baby's Breath). The G. repens (quite pink) has been blooming for a while, and will continue for while yet. They love the full sun, hot conditions - I have several at the front of the house (south facing).

The other Baby's Breath I really, really love is one called Rosy Veil. You can't grow it from seed - it's a cross between G. repens and paniculata. It grows more wide than tall, unlike paniculata. When in bloom they look like clouds in the garden, but you need plenty of space for them as they can easily reach 3' across but only about 18" in height. Again, they love the hot, sunny and dry and are long lived in the right conditions.

Finally, Limonium latifolium (Sea Lavender) might work as well. Although the leaves aren't big and round, they also aren't jagged or spikey (maybe a little pointy, but not spikey). They also produce airy clouds of bloom later in the summer - the foliage stays low but the blooms are held up high so it might be taller than what you're looking for.

Have you considered rodgersia astilboides tabularis? It has very LARGE rounded foliage! Plants are very hardy, though somewhat slow to establish. Be sure to plant in rich moist soil! See photo!

http://img.photobucket.com/albums/v34/Twrosz/000_35631.jpg

Thanks for the great suggestions everyone. Off to the greenhouse again. pretty sure some people must think I work there lol