(This is often said of something negative such as self-pity when no attempt is made to move beyond it. But it is also sometimes said without connotation just to indicate that someone has a lot of something such as money or luxury.)
Then he went down on all fours and crawled off, begging them to let him alone, and he rolled himself up in his blanket and wallowed in under the old pine table, still a-begging; and then he went to crying.
Chapter 6 (91% in)
wallowed = indulged in self-pity
There are no more uses of "wallow" in The Adventures of Huckleberry Finn.