We're going to have to get down and dirty, here.
Well, the easiest sort of spud to spot will probably be a potato:
whether in its natural growing form:
(these are potato flowers)
sliced thinly as crisps (as we call them in England):
in long rectangular prisms as chips (also known as fries), or sautéed, mashed, creamed, hashed, roasted, caked, boiled or baked.
If you're spud-bashing then you'll have no trouble spotting spuds because it means peeling potatoes. It's a British military term, to describe a spell of potato-peeling given as a punishment.
(Does this go to show that a soldier is less tough in some ways than your average housewife?)
Another sort of spud is a narrow spade designed for cutting through roots or digging up weeds. A spud (or spudder) is a tool a bit like a chisel for removing the bark from trees.
To spud can either be to use one of these tools, or, oddly, to start drilling an oil well.
Spud Island is more properly known as Prince Edward Island. I suppose it's because they grow spuds there.
Spot the frippet: spud. This word appeared in English as spudde in the 1400s, when it meant short knife. It was later used for the digging tool, and then by extension for the potato. The word is possibly connected to the Latin spatha, which means blade.
In the 1800s there was a group dedicated to keeping the potato out of Britain. It was called the Society for the Prevention of an Unwholesome Diet. It was named after the vegetable, not the other way round.