Spring gets the attention because of morels. Fall is the longer season and the more forgiving one for anyone starting out.
Timing
Fall foraging runs roughly September through November across most of the country, and the trigger is not the calendar. It is rain followed by a drop in night temperature.
The practical rule most people settle on: go four to ten days after a good soaking rain, once nights have started running cool. Before that window there is nothing. After it, something else got there first.
This is why foraging rewards going often and close to home more than going far occasionally. You cannot plan the date six weeks out.
Getting started without getting it wrong
One rule sits above the rest and it is not negotiable: do not eat anything you cannot identify with certainty. Not reasonably sure. Certain.
The way through that is not a phone app. It is a local guide, a regional field guide, and ideally a person who has been doing it in your area for years. Most regions have a mycological society and they take beginners out. That is the fastest and safest way in.
Plenty of people forage for years and only ever confidently take two or three species. That is a normal outcome rather than a failure.
Why a belt pouch and not a bag
Foraging is a repetitive motion. Walk, spot, crouch, cut, clean, stand, walk. Do it thirty times in an afternoon.
A backpack has to come off for every one of those, and it will not. By the tenth find it is hanging off one shoulder, and by the fifteenth it is on the ground somewhere behind you.
A belt pouch stays put. You reach into it without looking, one-handed, while the other hand holds whatever you just picked. That is the entire argument, and it is why most experienced foragers carry a pouch for tools and a separate open basket or bag for volume.
What ours is built for
Waxed canvas with full-grain leather trim, solid brass hardware, a paracord cinch, and a clip that puts it on a belt or a bag strap.
Waxed canvas rather than nylon because it sheds dirt, can be re-waxed at the end of a season, and can be repaired in a way nylon cannot. Brass rather than plated hardware because plating fails in wet grass within a year.
It folds flat when empty, which matters on the walk in, and opens wide enough to drop a find into without a second hand.
What people actually put in it is covered in what goes in a foraging pouch.
Two things that catch people out
Paper, not plastic. Plastic sweats. A good haul turns to mush inside an hour.
Permission. Rules differ between national forest, state land, BLM land and private property, and personal-use limits vary. Check before, not after.
See the pouch here: Foraging Pouch. For carrying seasoning to cook what you find, the Field Kit.