Progressing from my initial ideas of bottom-up worldbuilding, once you’ve established your geography, your basic flora and fauna, and then had your people rise up and spread throughout the world, you’ve more or less finished your paleolithic phase. Can you go into more detail here? Absolutely. Especially if you’re interested in doing stories that are paleolithic or paleo-to-neolithic-transition in nature.*
But odds are you’ll be ready to move into defining those neolithic cultures, and their multi-millennia transition to agricultural cultures– if that’s something they are going to logically do. And there are plenty of reasons why they wouldn’t.
Cultures don’t transition from hunter-gatherer to agricultural without good reason, mostly in terms of geographical conditions. Climate, water source and base foods that are easily domesticated all need to be present. Egypt had perfect conditions, for example, since you had the gentle Nile with predictable flooding patterns, allowing for easily irrigated and constantly renewed soil, as well as early native wheats to domesticate. As a contrast, southwestern Australia had similar environmental conditions, but no native plants worth domesticating.
And without some form of agricultural revolution, your cultures won’t progress toward civilization or past stone-age technology. I’m not assigning that any sort of value judgment– simply that the two go hand-in-hand. You can’t have a culture that remains hunter-gatherer but yet has cities with electricity and quantum computers.**
So, what foods can be the ones people eat and domesticate in this period? You can look to the “founder crops“, which were crucial in our Fertile Crescent, but that wasn’t the only place where agriculture appeared. There are other ways to go.
Fortunately, Lynne Olver has put tons of work into The Food Timeline, a website that is an absolute treasure trove of information. Pretty much every kind of food, she tells you when and where it came into use.
It’s important to remember this transition is a slow one, taking several thousand years, and once it get going, it tends to spread, at least along east-west lines. But that means a lot of things can be happening in your world long before anyone figures out to write it down.
*- Is Stonepunk a thing? If not, shouldn’t it be?
**- Not to poke at any specific Hugo-winning novel.