Green’s Dictionary of Slang

scumber n.

[dial. scumber, animal dung or sticky, viscous mud]

excrement.

[UK]Mennis & Smith ‘To a friend upon a Journey to Epsam-Well’ Musarum Deliciae (1817) 22: For here old Ops her upper face / Is yellow, not with heat of summer / But safroniz’d with mortall scumber.