Twisties, Cheezels, Chicos and Fantales ("fan" "tales") are probably the most typical Australian snacks in the box there. Shapes are pretty likely to show up on the table at a party, too.

Twisties - they probably should've sent you some chicken flavoured twisties instead of the cheese ones, since the chicken flavouring that is so predominant here in snack goods is somewhat unique.

Fantales - half the fun is reading the movie trivia on the wrapper

Cheezels - you need to put one on each finger and eat them like you're a fancy person with all your majestic rings.

Instead of whatever Arnotts cookie ('biscuit') they sent you, they should have sent you a pack of Monte Carlos... easily the most popular cookie in Australia.

Funny that he balked at the picnic bar, as the slogan for that for a whiel was "deliciously ugly". We also had these in Canada when I grew up - didn't realise they weren't sold in the US. Generally, you'll find Australian chocolate tastes a bit different to US chocolate - partly because of the anti-melting agents they have to add due to the heat here.

LPT: Smash up the violet crumble and eat it over your ice cream with caramel

Also, you got robbed on the TIm Tams. By far the #1 snack treat in Australia and they sent you the weird Tim Tam Fingers which nobody eats or buys.