ON URGE FOR Going - a track she now calls "the first well-written song that I have" - Joni Mitchell sang of the bone-deep need for escape that comes as the seasons turn. It's not just the geese "in chevron flight" on the move: there's also a man with "summer-coloured skin", or the singer herself, wrapped in blankets, forced to "bolt my wandering in". By the summer of 1965, the 21-year-old Mitchell had already covered a lot of ground in her quest for heat and light. She had left her home- town Saskatoon for art school in Calgary, before moving on to Toronto's folk music epicentre, Yorkville.

In February, she had given birth to a daughter, ultimately deciding to have the baby adopted; that June, she married folk singer Chuck Mitchell, moving with him to Detroit. Here, gripped by her first great burst of songwriting, she would head to a nearby diner called Toddle House to write, "always alone", sitting on a stool with a Coke. "Not looking for community?" asks her friend Cameron Crowe in the close-up interview accompanying this collection. "Looking for solitude," answers Mitchell.

Just how Mitchell carved out her own space, distinct from the folk scene's sometimes prissy, unfriendly codes and practices, away from the TV presenters calling her "ornamental", is the process beautifully captured on this 5-CD collection. Mitchell has been famously resist- ant to attempts to excavate her past, once describing a would-be archivist as a "burglar". Even now, in the liner- notes, she tells Crowe about people who own tapes trying to "stick me up", and the importance of beating "these leeches to the punch" - curation almost as a self-defence.

Yet if Mitchell was ever concerned she might give too much away, dilute or dissovlve, this collection of radio and TV performances, live sets and home recordings - including 29 previously unreleased tracks - does the opposite, enhancing the listener's wonder at her rapid evolution, shoreline to treetops in under four years. Organised chronologically (partly under advice from Neil Young), the collection stops before her 1968 debut, Song to A Seagull. That she has so many songs - not least Both Sides Now, Urge For Going, The Circle Game, even Conversation and Little Green (later on Ladies Of The Canyon and Blue, respectively) - that didn't make it to her first album suggests not only creative overspill, but also a remarkable clarity and confidence.

The oldest artefacts here are tapes made of pure- voiced, pre-art school Joan Anderson in Saskatoon in 1963 by DJ Barry Bowman, then lost for 50 years. There's a haunted china-doll version of House Of The Rising Sun; antique favourites John Hardy and Molly Malone, and Nancy Whiskey complete with indeterminate accent. The first live set, recorded at Toronto's Half Beat on October 21, 1964, keeps the woodsmoke-and- ale mood, featuring Woody Guthrie's Pastures Of Plenty and a particularly poignant Crow On The Cradle ("Somebody's baby is born for a fight"). "Folk music was easy to imitate," says Mitchell, "it was a good place to start".

Yet while an unaccompanied version of The Dowie Dens Of Yarrow would be demanded during a string change at one of the three sets on October 27, 1967, at Canterbury House, Ann Arbor, she quickly starts to pull away from trad arcadia. The second disc begins with a birthday tape she made in Detroit for her mother, Myrtle Anderson, in 1965. "I've written a couple of new songs since you were out here," she says, before singing Urge For Going, and the freewheeling, on-the-road canter Born To Take The Highway. On the demo recorded for Elektra's Jac Holzman that same year, featuring the moon-washed Let It Be Me, and her first composition, the autumnal Day After Day, there's The Student Song, its summertime tone weighted by yearning to be out in the world, ditching theory for practical experience ("Who can learn these silly words/When the creek begins to run?").

IT'S UNDERSTANDABLE why some of these songs fell away. Favourite Colour, recorded live for the CBC TV programme Let's Sing Out in not feel so compelling in a world that has Cactus Tree or Night In The City in it. Others feel properly lost: A Melody In Your Name is wonderful, an astringent pre- figuring of Song To A Seagull's bracingly mythic land- scape. What's The Story, Mr Blue? is a rowdy outlaw attempt at combining leftover lyrics, inspired by Bob Dylan; Jeremy, incomplete on a 1967 home recording, contemplates a prisoner's lot with sobbing inflections.

In a set from November 1966 at Philadelphia's Second Fret, Mitchell plays The Circle Game encouraging people to sing along to her response to Neil Young's prematurely gloomy Sugar Mountain (covered by her on Disc 3, in May 1967 at What FM, Philadelphia). Interviewers at the time seem concerned that her unusual tunings and vocal range might prevent artists covering her songs, yet Mitchell, ahead of perhaps the Me Generation curve, seems increasingly distant from the collective, the communal. On a home tape from New York, June 1967, she sings I Had A King, trans- forming her relationship with Chuck Mitchell into fairytale; there's Chelsea Morning's glorious colour-wheel detailing, or Conversation's brutal psychological acuity. They can be covered, but they're so specific, like picking strands from somebody's hairbrush, going through their clothes.

There's an intimacy throughout: the smudge of "Joni Improvising", the message to Myrtle, the anecdotes before the live songs. During the three sets from Canter- bury House, Mitchell talks about her father and his trumpet before I Don't Know Where I Stand, a witch and dancer Vali Myers before Ballerina Valerie's wild Blue-like timbre. Carnival In Kenora is introduced by a monologue about her imaginary Carousel-style Canadian musical. Yet charming through these transient flashes are, nothing feels closer than an untethered Night In The City, or the heavy, husky version of Little Green, four years and a world away from the girl who sang Molly Malone. Crowe asks Mitchell if she loves the young artist caught here. "I wouldn't call it love," she answers, "it's just part of the story." But what an opening chapter.

"I kept from time to time thinking, 'I wonder where those tapes wound up,'" said Barry Bowman, who made the first known recordings of Joni Mitchell when he was a DJ at Saskatoon's CQFC AM. The recording of the hour-long session was discovered 55 years later, when Bowman's daughter discovered a box of old tapes in his ex-wife's house and brought them over to her father - one labelled "Joni Anderson".