Blinkroot Seeds

The plant only pays out seeds while it is lit up. It flips in and out of that state on its own with no schedule you can plan around, so a farm of them needs checking rather than a timer. Cut one at the wrong moment and you keep the herb but get nothing back to replant, which is how people slowly lose their whole supply without noticing.

The yellow tips and the flickering glow are the tell. If it is dark and dull, walk past it.

They are not fussy. Dirt, mud, a clay pot or a planter box all take them, and unlike the herbs tied to a specific biome they grow anywhere you put them, so a row next to your alchemy station indoors is fine. For wild plants, the Staff of Regrowth pulls seeds off ones that have simply finished growing, which is more reliable than waiting for the glow.