Tom Thumb Lettuce Seeds. Heirloom Tom Thumb Lettuce is a butterhead type that makes small loose cabbage like heads. Plant Tom Thumb Lettuce and add beautiful 3 - 4 inch rosettes of bright green to your garden. The leaves of Tom Thumb Lettuce are tender and sweet. Tom Thumb Lettuce can be harvested at any stage of growth. 60 Days until full maturity. Packet contains approximately 250 seeds grown naturally with love and care. Happy Planting! We have a wide variety of Heirloom Vegetable, Herb, and Flower Seeds for sale. With all of our seeds: Your first packet ships for $2.50. All additional packets ship free. So your total shipping on a seed order is $2.50 no matter how many packets you order.