Tobold "Old Toby" Hornblower was a famous Hobbit of Longbottom in the Southfarthing of the Shire. In his younger days, Tobold was something of a traveller, and made the eastward journey to Bree on several occasions. It was there, it is generally supposed, that he came across the cultivation and smoking of pipe-weed. Tobold must have collected some of these plants and brought them back to his own garden in Longbottom. (At least, this is the most likely version of events - Tobold himself remained silent on the matter).
The Southfarthing seems to have been ideal for the growing of pipe-weed, and it became one the Shire's most important industries. Among the different varieties that were developed, one was named 'Old Toby' in honour of Tobold its first grower.