Green’s Dictionary of Slang

grubber n.1

[SE grub v./grub n.1 (2); note Yid. grobber, a coarse or rude person]

1. [late 18C–1940s] a beggar [grub v.1 (4)].

2. [late 19C] (UK tramp) an itinerant mender of old hats.

3. [1910s] work, presumably legitimate.

4. [20C+] a vagrants’ casual night shelter or workhouse.

5. [1920s+] (US) a disgusting person.

6. [1930s] (US) a working man [note also grub along under grub v.2 ].

7. see nail groper under nail n.1