traveling to US by road while PR card under renewal!

[escoss]

if I travel to US by road while my PR card is submitted for renewal, what documents do I need to show at Canada border in lieu of PR card. I was told by someone that landing papers (that are now slightly more than 5 yrs. old) are fine! is it true!
Can landing papers be used for this purpose!
If not, what will work for re-entry!
Thanks