A cheap and effective way is to use a modern LED torch/flashlight. In the past this wasn’t really a viable solution for three reasons; the light wasn’t truly white, the batteries were forever going flat, and when you dropped a torch with a filament bulb, the bulb broke.
Today’s LED torches, however, have eliminated all three problems. The light is pure white, bright and consistent. The LED’s use a tiny amount of power so the batteries last for ages. Drop a decent LED torch and it bounces rather than breaks. LED’s are thousands of times stronger than traditional bulbs and simply don’t break under normal use.
The better LED torches are water-resistant and allow you to change the beam focus, so you can go from tight beam to widely diffused one in the twist of a wrist.
Placed on the ground behind a flower, lichen or fungus it provides focused backlighting; held above the same items it simulates a beam of sunshine. What more can you ask for from a tiny metal cylinder?