Please identify this song for me.

I just heard a song on the radio, an old song, kind of southern-bluesy sounding. It had some nice harmonica in the background. The only thing I caught, lyrics-wise, was "Roosevelt", "bullfrog" and near the end the phrase, "the river was dark and muddy." And, if I remember correctly, the song started out with the moon rising.

Anyone know that song?

Would you be kind enough to post the artist, song title, and lyrics.
I ask for the lyrics because if I read them I'll know immediately if it's the right song.

Thanks for the help. Also, I would like to take a moment to apologize for being serious.

Every once in a great while I have a lapse.