if only foot tall, it still could be cutworms. They just attack the base of the stem and eat right through. They can eat through a full grown tomato stalk, I know that for a fact.
A quick way to stop them is to get some plastic cups, Cut the bottom off, then slice the cup up the side. Then just slip it around the base of the stem/stalk and bury it an inch or so in the ground.
Long/large nails work too