Native Species and Perennials.
Here is one lesson I learned the hard way and it took a few years to do it. If you are interested in planting flowers in your yard for beauty and food then consider perennials over annuals. For those that might not know, perennials will come back year after year and annuals only produce for one year, sometimes two. The purchase difference is perennials are much more expensive than annuals so it's very tempting to spend less money and go with the annuals. In the long run, however, you'll spend far less money if you go with perennials. If you have to, buy fewer perennials (than you would annuals) each year and just keep adding to them.
Native species are also important because 1). They are well adapted to the area and 2). Unless they are popular plants, they are probably slowly disappearing. I've planted endangered native species at my house including Jack-in-the-Pulpit (Arisaema triphyllum) and Fire Pinks (Silene virginica).
http://www.epa.gov/greenacres/wildones/handbk/wo19.html
