Robin Hood and the Tanner is Child ballad 126.
A tanner, Arthur a Bland, goes to Sherwood. Robin Hood appears and accuses him of poaching. They fight. Robin blows on his horn, summoning his men, and tells them that the man is certainly a tanner, as he has tanned his hide. They take him into the band.
In some variants, Arthur is related to Little John.
Broadside Electric recorded a version of this ballad on their 1995 album Amplificata.