In answer to your question about coneflowers, Echinacea, what you are experiencing is normal, they are deciduous, that is they die back in winter, and re-emerge late Spring. And they are perennials. So this is very common! Any varieties that you find in your local nurseries should do well in your area. A common variety, as shown in this photo is Echinacea purpurea. And make sure you amend your soil with a good planting mix or compost, mixed with your native soil, an good practice for most plants. Good luck! Here's a link from East Bay Times. http://www.eastbaytimes.com/2008/07/25/now-growing-echinacea/