"DO NOT LOG OUT WHILE DOING HIS TASK OR HE WILL GIVE YOU A NEW ONE!"
I logged out and logged in and I still get the same task.
If you don't like the task, wait a few minutes, then you get to change tasks

.
If your character said: "Sure! Just let me get it from bank", that means you have the item in your bank.
Another thing, while waiting for the patch to grow fully, you can talk to the farmer and he'll ask you to deliver a letter to Elstan in Falador, and he'll give you some seeds (I think they're random, but I managed to get 2 marentill seeds).
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meepster wrote:
Honestly, I don't understand the obsession with post count. I was made a Forum Moderator at less than 100 posts, so it shows how meaningless that number under your avatar truly is. Post count doesn't reflect intelligence, nor respect.