837: ragtag and bobtail Mar 24, 2017

It can sometimes be difficult to pin-down where phrases come from, especially as they pop-up and disappear from use so commonly. 'Ragtag', which now can mean 'ragged' or 'disorganized' as an adjective, and as a noun can be a synonym for 'motley' has stuck around for several centuries however. This phrase first began as 'tag-and-rag' and denoted the lower-class in the 16th century, and in the 18th, it was expanded to 'ragtag and bobtail' which is still used today. This variation retained its older meaning, but gained another sense as 'the whole of something' with 'bobtail' referring to the docked tail of a horse or a dog, i.e. "everything including the undesired parts". The phrase is not as often used in its expanded form today, but it still does carry the connotation of "undesirable and scrappy".

If you're interested in other words that historically related to the lower-class but have changed somewhat (then you have a very specific interest), but you can see these:
'peanut-gallery' or 'jacquerie'.