to what does the garden t\at the beginning allude?

The allusion is to the Old Testament Garden of Eden and the forbidden fruit. The most beautiful component of Lloyd's plantation was the garden, tended by four slaves. There was a plethora of delicious fruit and many of the slaves, from children to the elderly, could not resist breaking into it and taking a fruit. The Colonel tried to dissuade them by beating those he discovered, but this did not work well.