it happened to me too and I was on level 60+. I waited about two months for an update or a fix, but nothing happened, so I deleted the game yesterday and started again. I lost all of my progress. :(

you can also get some through daily login, but you only get around 50

you can find it by foraging sandy dunes :)

when you upgrade shelters and log cabin, there is a bigger possibility that people will join your community. You can also get people from daily logins sometimes :)

I think it's like this
Spring: Wheat, Carrots, Broad beans
Summer: Salad leaves, Broccoli, Peas
Autumn: Potatoes, Onions, Spinach
Winter: Cabbage, Cauliflower, Spinach