The last line of the chorus has changed over time. Most recorded versions replace Lead Belly's original "I'll get you in my dreams" with "I'll see you in my dreams," notably the Weavers (who hit number one with it in 1950, a year after Lead Belly's death), and hundreds of others; Pete Seeger, and Willie Nelson included. Tom Waits preferred "I'll kiss you in my dreams." Both a little less feisty than the original.
Such is the way of the old songs. People may change a word here and there to suit themselves but most of the time the overall gist of it remains the same.
The lyrics tell of the singer's troubles with ramblin' and gamblin' and (of course) love. But maybe the essence of the song is rooted in the phrase in my dreams. The words appear set into the song as something of a savior.
The song touches on the fact that we are all toughened from an early age to accept less than we might hope for. The world out there is a great equalizer when it comes to whether our hopes are realized or not. But the "in my dreams" part of the song gives us something of a key to that dilemma: that if we're tough enough, and just crazy enough, we might find that secret place inside of us where all hopes, both impossible and improbable, can be kept safe.
Because, if they're in our dreams, they can never be taken away.