Our World in Data has just published a great article about the source of the emissions associated with different foods.
It's a simple stacked bar chart. Each bar represents a food, and the coloured chunks represent where the emisisons come from - the key is at the top.
The main message for me - transport and packaging are a really tiny part of emissions for most foods. Turns out that "buying local" is much less significant than what you buy.
Other interesting infonuggets - cheese, chocolate and olive oil have very high emissions, and nuts are almost carbon neutral, because nut trees are replacing croplands.
Check out the full article, with lots of extra explanatory information, here: