Originally posted by Survivalgaming4life:

You can plant the carrot, for carrot seeds. Look at the variations in your farmer tool ui

In addition, 1 carrot seed planted gives you one carrot.
1 carrot planted will give you 3 seeds

Same goes for Turnips (found in the Swamp) and Onions (found in the cabins on the Mountain.

Flax and Barley 2 for every one planted.