Strawberries - about 5 yards, but they are nearly finished now. Otherwise about 20 miles.
Tomatoes, ours are not ready yet but I think the bought ones came from Kent.
Potatoes from Pembrokeshire.
However, I do remember many years ago being shocked that Cornish cauliflowers grown a few miles from us had travelled up to Covent Garden and back again.
Then, of course, we had the French cauliflowers which took over the market via the Roscoff ferry.
Now I notice that most of our cauliflowers are from Cornwall again.
Food may seem to have been produced locally but could have travelled quite some distance before arriving back in your local shop. Unless you shop at a local farm shop or grow your own, you may never know.