The same happened to me back in 1985 when I acquired a 1970 280SL with only 11K miles on it from an elderly lady who had a fall and broke her hip. She couldn't drive but had hopes and kept the car in the garage for two years before deciding to sell. I trailered it home and when first starting it up, about
four cups of dog food came out the tailpipes.
Luckily of course it hadn't gone through the motor but was stored in the muffler...the home of the mice. I guess they got free transportation and haven't seen them since!
300SE, 300CE. 190/5.0