First spot is one for farming Bomb Arrows.
Bomb Arrows are hugely expensive and really really rare in most places,
but I've found a good spot for em.
In the Akkala region, in the extreme northeast of the map, is Skull Lake.
Straight North of Skull Lake is a little teeny dark spot on the map.
That dark spot is an encampment of Bokoblins.
They're usually mid-high level Bokoblins, but they always spawn with Bomb Arrows.
If you kill them quick enough you can net around 10-20 free bomb arrows with each harvest of this spot. And if you've nabbed the Skull Lake shrine it's really easy to reach too. Plus there's always several environmental bomb arrows just dotted all over the camp too.
Gotten big stockpiles of 60+ Bomb Arrows just by visiting this spot every so often.
The second is one that might need a little explaining. Hearty Durians.
Cooking two Hearty Durians together gives you the single best healing item I've ever seen in the game.
Full Restore of all hearts+8 Hearts of buffer health. The healing on it is insane. And it just takes two Hearty Durians.
The spot is actually the Faron Tower itself. That little ledge immediately visible from the tower,
the ledge with the two partying Lizalfos and the Korok puzzle, has two Hearty Durians on practically every tree there.
If you need to farm for healing items, holy hell is this the spot for you. Every tree nets an item with Full Restore+8.