Seems like a lot of spring bulbs might fit your requirements….the adapted ones will be perennial, and bloom early
enough to be just about the only thing out (and so be quite valuable to
bees, etc.). Most go dormant in the summer and need no supplemental
water. A few have poisonous bulbs (such as the daffodil family) and so are reputed to be repellent to gophers. Look around and see which seem to be growing effortlessly in your area and start with those….