The "afla" part of the name derives from Aspergillus flavus, the first-discovered source of the toxin (in the 1960s). Aspergillum is the Latin name for a liturgical implement used to sprinkle holy water - it refers to the shape of the fungus when viewed under a microscope.
So, the name of the fungus translates to "yellow holy water sprinkler". Ew.
Aflatoxins are most commonly found in corn, peanuts, and cottonseed, but have also been found in almonds and other nuts and oil seeds, spices, figs, and dairy products. Animal products are sometimes contaminated by way of aflatoxin-contaminated feed.
The exposure to aflatoxins in North America, Australia, and Europe is minimal, but there is still some concern about long-term low-level exposure. And it is still a non-trivial concern in many countries; for example, cases of acute aflatoxicosis are an ongoing problem in Kenya.
Warm, moist temperatures favor the production of aflatoxins. Store nuts in a cool, dry environment.
Some methods of food processing help reduce exposure to the toxin, for example the alkaline conditions involved in making corn tortillas.
There is evidence that consuming apiaceous vegetables (carrots, celery, parsnips, parsley, chervil, etc.) can decrease the carcinogenic effects of aflatoxins.