These are classic Aussie foods with which almost every Australian child grows up.
Vegemite came into being during one of the world wars when it was discovered that the yeast sediment from beer production was not only edible (just), but full of healthful vitamins such as the B complexes. As soon as someone got the bright idea of actually spreading the stuff on bread and butter, they began producing it as a food item in its own right rather than simply canning beer by-products. It tastes a bit like gravy and Australians like teasing Americans by telling them that its like peanut butter, so that the unsuspecting American spreads far too much on their toast and grosses themselves out.
Milo is a vitamin enriched chocolate drink for children. Lumps of the stuff tend not to dissolve well into milk, so the company has decided to make this a selling point. Their animated mascot is an anthropomorphic chocolate lump which they have made into a doll and give away.
Both of these uniquely Australian food institutions are owned by American based companies.