Perhaps you mistook this word for stock or shook? If you took it for shock, you’d actually be OK, as shock is also used to refer to the same object. But that object is a stack or stock of sheaves or bales – that is, of grain. If wheat is bundled in sheaves and those sheaves are piled upright together in quasi-conical groups, those groups are called stooks; also, stook can be used to refer to triangular stacks of square hay bales turned on angle. The point of a stook is to let the grain dry and ripen, and thereafter it can be threshed (or thrashed).
So how does this thing get this name? Is it the stool-like shape? No. Are they reminiscent of a spook? No, but the word is. Must you stoop to make them? Irrelevant for etymology. Are they like a nose expecting a snook? Actually, if you think cock a snook, you chould come away from that with the cock as in haycock – which, being unbundled, is not a stook, however it may be mis-stooken. The echoes go on and on, but this word, anyway, is of Germanic stock, though not exactly Germanic stock – rather stûke. It’s a sturdy word, stocky even, quite opposite to the delicacy one gets from the sound of kotos (Japanese stringed instruments). It has a pair of angular letters for voiceless stops guarding the goggling oo, and is strengthened by the sliding in of the /s/. Its vowel sound being that of took rather than of spook, it lacks the length and lunacy of [u]. Rather, its sound is like that of the word stuck as said by a Yorkshireman: “Here! What’s the stuck in the middle of the field?” “That stook in the middle of the field?” “Yes.” “It’s a stook.” “Well, I see it’s stuck there, but what is it?” And so on.