Lady's mantle is an old fashioned mounding plant, grown for its beautiful fan shaped hairy olive green leaves that collect dew drops on the edges and center, giving it a magical appearance in the morning light. Flowers are a yellowish green, flopping about somewhat. In my California garden it is too hot and dry for it to self sow, but in cooler and more humid climates this plant can become rather invasive.
Lady's mantle needs some afternoon shade in a hot garden - we often put in full shade and it does well. In the Pacific Northwest or the Northeastern U.S. it does fine in more sun.
Lady's mantle is an ancient medicinal, not used much anymore for medicine making. A funny story though...
I attended a 'High Tea' at a garden in northern Mass. a number of years back. It was the end of July, hot and humid, and about 50 of us were in a room with no air conditioning, drinking hot tea. The elderly woman who was hosting the tea walked us around her garden, wearing a wool skirt, long sleeved shirt and stockings, cool as a cucumber. I was dying in shorts and t-shirt. She stopped by the lady's mantle and told us that the plant was 'magical'. Whatever. But then, perfectly straight faced and sweat free, she said "If you take the dewdrops from this plant at midnight on the seventh night of the seventh month and drink it, you will live forever." Wow, everyone was silent. The heat had finally done her in. Then, perfectly straight faced, she added "Oh yes, you must be naked when do this." Everyone erupted in laughter, but I am pretty sure she meant it. Sure enough that I do this every year!