best thing i ever found in an old shed in the garden was a rusty billhook that cleaned up just lovely; brilliant for attacking the jungle! i use the straight edge to chop kindling too, better than a hatchet any day, though the postman is now a little wary when i went to the door with it in my hand after having been sharpening it.....
somewhere under the garden is an old air raid shelter which was, allegedly, just planted over. I've never found it though and i used to dig pits regularly when i was a kid, looking for archaeology. my parents let me excavate the victorian midden when i found it, which was fascinating; one blue bottle marked 'poison' - almost as good as a body - heaps of 'marble' bottles and broken bottles, china, bones, and one cut glass perfume bottle slightly chipped, though still intact, with what turned out to be a silver lid. glass and china is about all that really survives our acid sandy soil though; but i have found quite a few horseshoe nails, as there used to be a right-of-way across our garden in the pre-wwI era to a paddock. this is why i keep my tetanus WELL up to date; higher risk than normal!