Here are some contacts that I´ve found in Kassel. These are people that organize volunteers in Kassel and can connect you to the right people. I think Vellmar may be the closest to where you are:
Oberweser:
Cornelius Thurrey
Telefon. 05572/9373-16
Vellmar:
Oliver Ulloth
Telefon: 0176/24282978
Hofgeismar:Janwienand@gmx.de und christoph-vialon@freenet.de
Wolfhagen (Stadt und Region):
Dekan Dr. Gernot Gerlach
Telefon: 05692/996630
dekanat.wolfhagen@ekkw.de
Bad Karlshafen:
Lisa Borchert
Telefon: 05572/9219062
Here is also an organization Flüchtlingehilfe Kassel:
****://***.fluechtlingshilfe-kassel.de/
There is information on their website (that will be more specific to Kassel) and you can contact them here:
****://***.fluechtlingshilfe-kassel.de/are-you-a-refugee/contact-us/
It looks like they are also organizing a concert/lunch in the area on June 9th! The first post on the website explains that there are inviting some people to a concert on one day, and on the next want to have a music exchange and lunch on the next. The contact for this event is:
dinafalten@gmx.de