Currently theiving NPC's that give items other than coins can be rigged to give only one item (Ex, master farmers).
1. Grab one seed, for example, a limpwurt seed.
2. Have it be the only seed in your inventory and fill the rest with anything else.
3. Spam click a farmer until you no longer get the message "Not enough space in your inventory". You player will thieve when the seed you wish to have (one in your inventory) id is selected.