A nice post on an early agile-like team:

http://marcatopartners.com/2010/03/11/birthplace-of-agile/

I’m referencing it in case you have “earlier documented descriptions of Agile teams.” 1981 is pretty early, but I can imagine that the earliest software development teams were more like agile than they were like a more formally structured “waterfall” or “heavy weight” (remember when agile was called “lightweight?”) methodology.