Jenny Everywhere's mother
According to some accounts, Jenny Everywhere had a unique mother before being splintered across the Multiverse; she retained her goggles and scarf, duplicated across the multiverse to infinity alongside Jenny herself. It was claimed that this original mother was “a famous aeroplane pilot until she disappeared”.
Across her incarnations in the Multiverse, Jenny had an infinity of different origins and childhoods for her individual selves, many of whom had individual mothers of their own. Amelia Midnight and Princess Katerina Corwin were Jenny's mothers in a high number of universes; when the Multiverse was temporarily reduced to a single Collapsed Cosmos with a single Jenny, Amelia and Katerina were the mothers she primarily remembered as her parents.
Biography
Accounts of Jenny's “original” mother
One version of Jenny Everywhere once noted that her mother had been "a famous pilot" until she disappeared. (COMIC: The Late Shift) Another, while suffering from shifter hangover, got a glimpse of memories of another Jenny who had grown up on a farm in Pennsylvania and was fascinated by her mother's old biplane which was hidden behind the barn. (PROSE: Morning After)
According to Jenny Everywhere: Secret Origins, a comic book, Jenny's original mother was a woman with light blue-green eyes and reddish-brown hair. She often wore over her head the scarf which her daughter would later inherit from her and wear around her neck. Still according to the comic book, she climbed to a high rank in the military hierarchy of "the oldest and most advanced Earth" in the multiverse and married a scientist who was himself held in high regard, although not quite as much as her. (COMIC: The Secret Origin of Jenny Everywhere)
She had two daughters: one, the elder, being the one who would one day call herself Jenny Nowhere, and the other, younger, being Jenny Everywhere. Jenny Everywhere later remembered eating toast for the first time in their mother's kitchen while she was six years old. (PROSE: Memories of Nowhere)
Jenny Everywhere: Secret Origins recounted that Jenny's mother was one of the only individuals to believe her husband, a scientist, when he discovered that a mysterious, intelligent force of destruction was eating away at the multiverse and might soon destroy their universe. She helped him place their young daughter, barely more than a baby, in the Pod he had constructed, which would allow her to survive the destruction of her home Earth at the cost of splintering her across the multiverse. Shortly after, the dark force consumed the home universe, Jenny's mother included. (COMIC: The Secret Origin of Jenny Everywhere)
However, Jenny Everywhere later visited her mother's now-empty kitchen for the first time in "centuries", showing that this account was unreliable and Jenny's childhood homeworld was not in fact permanently destroyed. (PROSE: Memories of Nowhere) Indeed, when Retro asked Jenny if the tale related by Jenny Everywhere: Secret Origins was really how it had happened, she evasively answered "Eh… kinda". (COMIC: The Secret Origin of Jenny Everywhere)
When the Jenny Everywhere of Reality 18 was transported by the Key of Enecloog to a hellish mindscape of all her dark thoughts, she heard “angelic voice ”of her and Jenny Nowhere's mother, speaking “above me, so distant, telling [them] that Jenny and I are at stake and that God isn’t afraid”. (PROSE: The Apocryphal Journeys of Jenny Everywhere)
Across the Multiverse
Amelia Midnight and the Princess Katerina
In a number of continua, Jenny's origins were variations of a single familiar story. In these universes, Jenny was the (sometimes adopted) daughter of Captain Amelia Midnight, a famous inter-dimensional adventurer in her own right, captain of the hypership Zephyrus. Having a number of enemies, Captain Midnight would then hide Jenny away on the interdimensional isle of Barbelo, to be raised by Princess Katerina Corwin, Amelia's primary love interest, and, secondarily, other partners of hers. She would take on the “Corwin” surname.
In the Collapsed Cosmos, this origin seemed dominant for the “collapsed” Jenny, who recognised a version of Amelia Midnight who had retired at the End of Time (and who was an amalgamation of all of Amelia's selves) as her mother. (PROSE: The Hermetic Garbage of Jenny Everywhere)
Mrs Jacobs
In one universe, Jenny Everywhere grew up as “Jenny Jacobs”, the adopted daughter of Simon Jacobs and his wife. Mr and Mrs Jacobs had two other daughters without any special abilities, Julie and Jordan. (PROSE: The Jenny Everywhere Chronicles) Several other versions of Jenny with similar backgrounds, including the adopted sister Julie, existed. (GAME: The Jenny Everywhere Roleplaying Game, PROSE: The Hermetic Garbage of Jenny Everywhere)
Mrs Werth
In at least two known universes, Jenny's birth name was “Jennifer Evers-Werth”, with the “-Werth” hyphenation being her mother's name. This mother disappeared in mysterious circumstances, in a repeat of a common pattern across Jenny's infinite lives, where one of Jenny's parents would disappear mysteriously when she was young, setting her on the path to adventure. In one such universe, Jenny, while born as Evers-Werth, stopped using the hyphenation after her mother's disappearance. (PROSE: Past Prologue)
Mrs Bainbridge
In one universe, Jenny's mother was married to a British man called Mr Bainbridge. She was a strict, driven mother whose determination for Jenny to succeed in school put her at odds with her daughter as she insisted that Jenny cut her fantasies and whimsy out of her life to focus on her coursework. (PROSE: The Genesis of Jenny Everywhere)
Molly Everton
In the 38167th Universe, Jenny Everywhere and Jenny Nowhere's dopted mother was Molly Everton. Her maiden name was Stropcliffe, being the daughter of Sophie Stropcliffe. (PROSE: Family Business)
Self-parentage
Occasionally, the mothers of individual incarnations of Jenny were themselves Jennies.
For example, one Jenny, who flew a high-tech biplane, ended up disappearing while leaving a daughter behind in Pennsylvania. As she grew up, the daughter-Jenny began to be able to tap into her late mother's memories, ultimately allowing her to figure out how to fly the biplane. (PROSE: Morning After)
The Jenny who was a classmate of U.R. Hip once claimed to be her own parents, without going into detail about how that worked. (COMIC: Albany Gets PWNed)
Behind the scenes
The intended implication of the description of Jenny's mother in COMIC: The Late Shift as "a famous pilot who disappeared", and was known for wearing goggles and a scarf, is that Jenny's mother was somehow Amelia Earhart or a parallel universe version thereof. Interestingly, in COMIC: Say The Word, Jenny has what appears to be a photograph of Earhart hanging on the wall of her house.
Because "Jenny Everywhere's mother," on the face of it, is an extremely vague concept defined by her relationship to an open source character, the broad idea of "Jenny Everywhere's mother" can be considered an open-source character, although the visualisation of her in COMIC: The Secret Origin of Jenny Everywhere is not open-source.