Almost everything modern readers know about Laima rests on a single, extraordinary body of source material: the Latvju dainas, a collection of Latvian folk songs assembled chiefly by the nineteenth century folklorist Krisjanis Barons, who spent decades gathering, sorting and publishing short traditional verses collected from oral tradition across the Latvian countryside, ultimately compiling well over two hundred thousand individual dainas, many concerning Laima's role in birth, marriage and fortune, into a multi-volume edition and an accompanying physical filing cabinet of index cards, the Dainu skapis, that Barons used to organize the material by theme. That cabinet and its archive were formally recognized by UNESCO, inscribed on the Memory of the World Register in 2001, in acknowledgment of the collection's unique scale as a record of Baltic oral tradition gathered while rural singers still preserved a large body of pre-Christian mythological material within ordinary song rather than as antiquarian record.
Because Laima's theology survives so heavily through this one systematic nineteenth century collection effort rather than through medieval chronicle or continuous learned commentary, scholars studying her are, in an important sense, reading Barons's organizational choices as much as the songs themselves, since how he grouped and arranged tens of thousands of verses shapes which patterns modern readers can see in the material at all. The scale of the underlying archive, still housed at the National Library of Latvia and the source for most scholarly and popular writing about Laima, makes her one of the better documented, if only recently and systematically documented, figures in Baltic mythology.