I have a couple...
-Elves are born from the fruiting bodies of a mature "elven tree", more accurately, as a type of mold. This mold is not actually intelligent, and it grows rather quickly (one of my players used one as a wig. He was the equivalent of a warforged powered by PURE BELIEF. Remind me to tell you about the setting some time.). It then develops a humanoid body, without mammary glands (duh), and with the typical plant hair. They then enter into sexual maturity for a couple months, during which time, they develop a rather... strong sex drive, leading to nymphomania and satyriasis (designated by APPARENT gender. They are genderless.) They then slowly stiffen into actual trees later on. They also get natural druidic casting because, well, they are talking to their relatives.
-Elves are a mostly peaceful race, split into three types of densely interlocking groups (religious cults, blood-family tribes, and soul-family bands, of which an elf can be a member of each. Makes any wars that actually happen very awkward, as they tend to not want to kill anyone who are in the same grouping as they are), whose elementary social group is the triads. They each have a natural necromantic ability, which gets stronger within a triad; in my world, they "invented" the Necropolitan ritual. A single small web of warlike tribes, bands, and cults, known as the Singular Horde, invaded halfling lands (halflings invented cities), and through the forced mating of elves and halflings came gnomes. The Singular Horde then fell into debauchery and thorough self experimentation, they created orcs and humans (staunch allies and friends in my setting), who then overthrew them. As such, being an elf (or half-elf), means that you are practically Public Enemy No. 1; this has led to... problems with the tribes, bands, and cults not involved in the Singular Horde.