Leaderbrand is offering $2 off their Ready to Eat, Prepacked potatoes, beetroot, or sweetcorn. This coupon was in today's Herald page 61. That's the e-version of the paper which can be read through Pressreader (should be free via your local library).
Countdown is currently selling the potatoes for $1.99 so with the coupon, makes it free.
Beetroot is 2 for 7, or $1.50 each after the coupon.
Sweetcorn is $2.99 or $.99 after coupon. This isn't on sale so there is a good possibility you should be able to pick this up for cheaper.
Coupon doesn't expire until November 30. Coupon should work at the other supermarkets but not sure what the prices are.
EDIT: Also see in June 29 Edition of NZ Herald
It says copies are not valid.
How do we use this voucher (even though I can see it in pressdisplay.com link)