There is an urban legend from Alabama that German subs were able to beach in order for the sailors to visit relatives. There is a population of German-Americans in Baldwin County, which sits on Mobile Bay and the Gulf. Supposedly, this happend during WWII, but I have never seen any actual proof and I google it from time to time when I think about. What say the experts?
FYI- This is a pretty cool sub-reddit. I think I may have to subscribe.
While German submarines did operate extremely close off of the Gulf and East coasts during the war, especially in early 1942, I haven't seen anything about submarines actually tying up onshore or getting crew on land. Such a thing would be very difficult to coordinate with any sort of civilian relatives onshore (it took around 3 weeks/1 month to cross the Atlantic), a pretty big risk to the submarine, and unheard of in any other theater. So the short answer would be no.
However, there were a few occasions where German submarines dropped off covert agents and operatives. For example, in May 1942, the submarine U-213 dropped off a covert agent in New Brunswick, to monitor ship movements for the Abwehr. The linked website is a fantastic and reliable resource for most things German submarines, in both World Wars.