The flower you sent with your note is common tansy. It's an herb that's been growing in gardens since colonial times. In fact, colonists used to plant it near their door to help keep ants out of the house. The leaves are often dried and used in potpourri. The flowers are very long-lasting when cut and are also good dried flowers, retaining their color well.
Common tansy grows best in full sun to light shade.
Q. My bleeding hearts did fabulous this summer until now. Thanks so much. The yellowing leaves on common bleeding heart this time of year is perfectly normal. About this time of year, and sometimes earlier in the summer, especially if it's hot and dry, the leaves turn yellow, then die. When this happens, it leaves a large hole in the garden, so I always recommend planting annuals around it so there will be something there to take its place once it goes dormant.