things to look at under a magnifier

Get yourself a good 5X to 20X magnifier, and go out and look at stuff. I really like this one, but any loupe with lighting is good.

human-made

• $20 bills, $10, $5, ...
• cloth has different weave patterns [1] [2] [3]:
  • plain weave
  • balanced fabric
  • twill
  • double cloth
  • Oxford — often for men's shirts
  • gabardine — twill wool, used for suits, overcoats, windbreakers, outerwear, etc

naturally-occurring

While hiking:

• things that grow on trees:
  • lichens identification/classification, example photos, how to identify, photos,
• geology

Other-wise:

• identify lumber species [1] [2] [woodidentification.net]