Leaving the Island
Though more common fruits and vegetables are available during the game, players must complete certain tasks to retrieve or use items. Ginger, for instance, can be planted but not harvested until your Sim has left and returned to the island on the pirate ship. The same is true for wheat seeds, because they are unlocked only upon your Sim's return.
Cut Scene
After leaving the island on the pirate ship, you will have to endure a cut scene celebrating your accomplishment. Once the cut scene has ended, click on the button that offers a return to the island. Upon your return, additional products and services will be available from the other Sim characters.
Fishing
Fish for koi in the pond with your fishing pole. Save up as many fish as you can, then visit Mrs. Weeder and exchange your fish for wheat seeds. You can also catch fish by crafting a bamboo spear and selecting the option to "Stab" the fish.
Plant
Once you have traded Mrs. Weeder for your wheat seeds, plant them. The wheat seeds will grow in two days, after which you can cut down and harvest the stalks. The more seeds you trade for, the more wheat you can grow.