TREES

~Telperion [tehl-‘peh-ree-on] – the elder of the Trees. Its leaves were dark green above and silver beneath; its last flower became the Moon.
Also called: the White Tree
You know it from: Aragorn mentions it when he finds the sapling of the White Tree.

~Laurelin [‘low*-reh-lin (*- ‘ow’ as in ‘cow’, not as in ‘low’)] – the younger of the Trees. Its leaves were light green with golden edges; its last fruit became the Sun.
Also called: the Golden Tree

Galathilion [gah-lah-‘thih-lee-on] – image of Telperion made by Yavanna for the Elves; grew in their city of Tirion; all the other White Trees are descended from it: the celeborn, the nimloth, and the White Tree of Gondor.
You know it from: the history of the White Tree is mentioned by Elrond during the Council; it is the Tree of the High Elves that is carved in the west-gate of Moria. (FOTR)

Celeborn of Eressëa [‘keh-leh-born] (“tree of silver”) and Nimloth of Númenor [‘nihm-loth] (“white blossom”) are both descendants of Galathilion (above); its sapling was brought from Valinor to the Elven isle of Eressëa, from there to Númenor, and from Númenor to Middle-earth by Elendil and his people .
You know Nimloth from: referred to as ‘one white tree’ in a song sung to Pippin by Gandalf on their way to Minas Tirith (TTT); mentioned by Gandalf as Aragorn finds the sapling the White Tree (RotK).

Also around were the mallorn (plural mellyrn) trees (Gondolin, Númenor, from there brought to Middle-earth where they thrived in Lothlórien).

FLOWERS

Niphredil- [‘nih-freh-dill] – an everblooming white flower in the forest of Neldoreth in Doriath that bloomed first when Lúthien was born.
You know it from: Niphredil also grew upon Cerin Amroth in Lothlórien.

Also around was athelas (kingsfoil), a plant with healing properties used in LotR; it is mentioned by Aragorn as coming from Númenor.