Thomas Schuhmacher has a paper on a knot-headed pin from a Bell Beaker context in Fez, Morocco.
He dates this pin to around 2300-2000 B.C. It appears that knot-headed pins were used to fasten clothing at the neck as indicated in European burials, replacing the bone toggle. [See Stuart Piggot here]
As you can tell from the map below, a different style was popular in Atlantic Europe, which may have been the wheel and cross pin-head, which looks like a big letter opener.
Although not shown in the map, Gordon Childe commented a little more in depth on knotted pin-heads of pre-dynastic Egypt, the Upper Euphrates and the Indus [here]. There is also a single example from Tunisia, not shown. The European examples are from the Early Bronze Age or a little earlier for those of copper.
It's interesting that the distribution roughly squares with the "bow-shaped pendant" [here] which also seems restricted to east of the Rhone, except again, Morocco with another single find.
Both objects could have an origin, or at least very early representation, in SW Egypt. [here] Hippo tusks or bone were also carved into some sort of similar, non-functional device. This could be the result of trade along the Rhone to places like Tunisia.
It seems the Beaker cultures to the left or right of the Rhone and Rhine quickly developed unique fashions for their regions. This map may show how trade influenced these differences in style.
Dancing in the Dark? The westernmost “Cypriot” knot-headed pin
from Aïn Smene (Morocco). Thomas X. Schuhmacher
Universidad Autónoma de Madrid, 2014 [Link]