For 4 days in the middle of Spring (15 to 18), you can find a great quantity of salmonberries in bushes everywhere around. Most will be found in the forest south, but there are many at the hills near the cavern, in the farm and around Pelican town.
Salmonberry is a not a good fruit for making money, but at 25 energy per unit, it is a great source of energy in the early game.
Maximising your harvest
During the 4 days, make salmonberry gathering a priority and make sure that you forage in all locations that have bushes (farm, forest, hill and town).
Each bush will give you 1 salmonberry, and 1 additional unit for every 4 Foraging skill level that you have.
Knowing that, getting to Foraging level 4 makes for a good goal in the very first Spring, as it literally will double your salmonberries harvest.
How many salmonberries will you find?
25 bushes per day shouldn’t be too hard to find, for a total of 100, 200 or 300 salmonberries in total. You can easily find more if you try harder but I found that to be a fair number of bushes, without trying too hard.
What should you do with it?
As they are worth very little money, the main use of your salmonberries should be energy. For example, if you harvested 100 of them in the first spring, you can get 2500 energy by eating them (25 x 100)… which is pretty close to the energy you get from 10 days.
It’s a lot!
A secondary use would be as a gift for friendship. Quite a few villagers like salmonberries (check out the list here) and if you transform them into jelly, almost all villagers will like it.
It’s a great way to improve friendship, without spending gold.