Suem, Ferling, Grasson

In a copy of Court Roll, dated the 40th year of Elizabeth, and relating {8}to the manor of Rotherfield, co. Sussex, these words occur:— "R. K. cepit extra manus domini unam suem trẽ nat' de ferling," &c. I shall be obliged to any of your correspondents who will explain the words *suem* and *ferling*. What is the etymology of *grasson*, a word used in some north-country manors for a fine paid on alienation of copyhold lands?