I have compiled a list of sources for the elements that are available to the amateur chemist. Fluorine will be discussed here.
Fluorine is the most reactive element. It is an extremely powerful oxidizing agent. It is a yellow-brown toxic gas. Fluorides, its only set of chemical compounds, are much less reactive and are moderately toxic. Teflon contains fluoropolymers. Toothpastes and drinking water contain fluoride compounds.
In element form: No sources found.
In compound form: Calcium fluoride is found as fluorite, a common mineral. Most toothpastes contain fluorides. Whink rust remover is a dilute solution of hydrofluoric acid.
Here is my sample of fluorine. It is toothpaste containing about 0.3% sodium fluoride.