Engine almost out of oil - valve damage caused?

Ello!
After taking my Montero for an oil change I was informed there was less than a quart of oil in the engine and it had metallic shavings in it. The oil light never came on and I checked it a few weeks before and the oil level looked normal. Three weeks or so before the oil change it started to make very loud engine noises and was running rough. After the oil change the loud noise is gone but there is a slight clicking noise. My mechanic is insisting we have it checked out for valve damage but I'm hesitant due to the cost of the repairs, etc. Could you advise the potential issues oil starvation may cause? Or symptoms of starvation? Anything to give an idea of what to expect would be great. Thank you!