Hie thee to a German butcher and ask for weisswurst; these are sausages made with brains, although I don’t know if they’re beef or pork. (The weiss- part of the name refers to their color.)
These wurst are pretty bland-tasting, so you should eat them with a good, strong mustard. On the other hand, grandma always used to say that plain weisswurst were just the thing to eat if you had an upset stomach. I can’t vouch for that personally, though, because the last thing I’d want to eat on an upset stomach was sausage. 