I have lists for many of this names, but I’ll pick out the ones I like best.
Tree (Eccentric Botanical Names for Girls | Nameberry & Arboreal Names - British Baby Names): [name_f]Acacia[/name_f], [name_u]Ash[/name_u], [name_u]Bay[/name_u], [name_f]Cassia[/name_f], Cordyline, [name_f]Ebony[/name_f], Evodia, [name_f]Fern[/name_f], Halesia, [name_f]Hazel[/name_f], [name_f]Holly[/name_f], [name_u]Juniper[/name_u], [name_f]Laurel[/name_f], [name_f]Maple[/name_f], [name_f]Myrtle[/name_f], [name_f]Olive[/name_f], [name_f]Palmyra[/name_f], [name_f]Plum[/name_f], [name_u]Sequoia[/name_u], [name_f]Willow[/name_f]
Birds (Avicultural Names | Nameberry): [name_f]Alouette[/name_f], [name_f]Canary[/name_f], [name_u]Dove[/name_u], [name_u]Finch[/name_u], [name_f]Lark[/name_f], [name_u]Raven[/name_u], [name_f]Sparrow[/name_f], [name_f]Starling[/name_f], [name_u]Teal[/name_u], [name_u]Wren[/name_u]
Gems (Solid as a Rock Names | Nameberry): [name_f]Agate[/name_f], [name_f]Beryl[/name_f], [name_f]Emerald[/name_f], [name_f]Garnet[/name_f], [name_f]Jade[/name_f], [name_f]Lapis[/name_f], [name_f]Opal[/name_f], [name_f]Peridot[/name_f], [name_u]Ruby[/name_u], [name_f]Sapphire[/name_f], [name_f]Topaz[/name_f], [name_f]Turquoise[/name_f]
[name_f]Earth[/name_f]-y (British Baby Names: Nature and Plant Names): [name_u]Bay[/name_u], [name_u]Brook[/name_u], [name_f]Delta[/name_f], Fallow, [name_f]Marina[/name_f], [name_f]Meadow[/name_f], Moraine, [name_u]Prairie[/name_u], [name_u]Reed[/name_u], [name_f]Savanna[/name_f], [name_u]Sierra[/name_u], [name_f]Valley[/name_f]
[name_f]Celestial[/name_f]: [name_f]Breeze[/name_f], [name_f]Dawn[/name_f], [name_f]Hurricane[/name_f], [name_f]Rainbow[/name_f], [name_u]Sky[/name_u], [name_f]Snow[/name_f], [name_f]Soleil[/name_f], [name_u]Sunny[/name_u], [name_f]Sunshine[/name_f], [name_f]Tempest[/name_f], [name_f]Tornado[/name_f], [name_f]Windy[/name_f]
For astronomical names, I would use the zodiac sign: [name_u]Gemini[/name_u], [name_f]Lea[/name_f] ([name_m]Leo[/name_m]), [name_f]Libra[/name_f], [name_f]Urania[/name_f] (Uranus), Virgo
Check out http://www.hippy.com/modules.php?name=News&file=article&sid=58 for other nature names besides the ones listed.