Nature names have stayed in fashion for two decades and counting because they do something specific: they evoke a quality without describing it. A name like "River" suggests calm and depth without anyone needing to say so.
Trees and plants
Hazel, Rowan, Willow, Linden, Olive, Sage, Juniper, Forrest, Cedar, Aspen.
Water and weather
River, Brook, Lake, Rain, Storm, Sky, Marin, Kai (sea, Hawaiian/Japanese), Maris.
Birds
Wren, Robin, Lark, Finch, Phoenix, Mavis.
Stones, earth, and light
Flint, Onyx, Jasper, Pearl, Sterling, Aurora, Soleil, Linnea (twinflower).
Seasons and times
August, Winter, Autumn, Summer, Dawn, Tamsin (twin), Avalon.
Try the nature theme for the full list.