Where did Naomi send Ruth at night to lie down at Boaz's feet?

Answer: The threshing floor

Boaz was winnowing barley on the threshing floor. Ruth uncovered his feet and lay down after he had eaten and gone to sleep.

“Now is not Boaz, with whose servant girls you have been working, a relative of ours? In fact, tonight he is winnowing barley on the threshing floor.”— Ruth 3:2 (BSB)