Tom demands treasure. Poor little leprechaun... But of course he knows where a treasure is hidden!
The leprechaun leads him to a field full of boliauns. It's right under this boliaun plant, the leprechaun insists. But Tom doesn't have a spade, so he ties his garter (a little belt that holds up your socks) around the plant before he runs back home to get it. When he returns, he finds the leprechaun gone, and there's a garter tied around every boliaun in the field!
This is a knot to go at the end of the story.