I have traced my family back to year 1500 in Sweden. Many emigrated to US and after year 1900 some changed spelling from Grufman to Gruvman, which is how it's pronounced.
Some immigrants came from Ukraine (former Russia and Prussia). The link between them and Sweden is still not clear, but a theory is that some Swedish soldier with name Grufman was left by there during some of the many wars that Sweden were involved in. That research goes on.
Currently there are some Grufman and Gruvman in IL.
I don't know them, but if anyone wants to know their roots in Sweden they can contact me on firstname.lastname@example.org
I can also do research for anyone who wants.
I own the Emigrant CD and will do look ups. Name and parish or year of immigration would be helpful. Email me