This is my very favorite -- it's Winecup, or
Malvaceae, in the Mallow family. The vibrant blooms are stunning against the spring backdrop of green foliage and they just seem to pop right out of the landscape when you see them. And, as a bonus, it's a spreading, drought-tolerant perennial, which makes it perfect for me here in Central Texas.
I actually have two different varieties in my rock path. As you can see from these two close-up photos, the leaves on these two are dramatically different.
I never tire of these, but some years I do lose them to a bunny salad!