The intellectual mathom collector

If you've lived long enough, read widely or suffered through the usual collegiate education requirements, you may find that your head has vast stores of disconnected knowledge which don't necessarily relate to anything necessary for daily life. That is, until the moment some dusty lump of data becomes a relevant jewel.

J.R.R. Tolkien coined the word "mathom" to describe questionably valuable clutter that you can't throw out:

Mathom
Last but not least, here’s a word you can use to switch up your everyday vocab. Next time you go to visit your grandparents, keep your eyes peeled for mathoms, a popular Hobbit possession.
Mathom comes from the Old English ‘maðm’, meaning treasure, which fell out of use in the 13th century. In the Shire, it’s commonly known as a Hobbit’s trinket, typically a useless heirloom. Tolkien went further and revived ‘mathom-house’ as a museum stuffed with old curiosities.

Do you find yourself collecting and seeking out information in odd corners just on the off-chance it will be useful?

Have you a story of the time when some obscure, trivial factoid suddenly saved the day?