St Paulinus was a missionary in the 7th century. One day he was riding his ass along the ancient trackway above Caistor. The ass was more obstinate than usual because it hadn't had any breakfast. St Paulinus saw a man up ahead who was sowing corn. Perhaps he would share some of the grain? He asked the man for some corn from the sack in the field. 'Oh that's not a sack,' replied the farmer. 'That's - a stone.'
A stone, eh. 'Then stone it shall be' retorted St Paulinus. And so it was. Apparently it stayed in place in the field for many generations, and then a farmer decided to move it off his land. It was practically immoveable and took a whole team of horses to shift. After that every misfortune imaginable fell on the farm. The farmer thought he'd better replace the stone. This time an old horse managed to drag it up the slope easily by itself.
It's also said that various other people who've damaged it have come to a sticky end, like one of the builders of the nearby Pelham's Pillar in the 1840s, who chipped a bit off and then mysteriously fell from the pillar and was killed.
The stone is supposed to have a 'gathered' effect like the mouth of a sack. Can anyone track it down??
The picture from C. Phillips report on Lincolnshire published in 1932 says that the stone stood 'until recently' which would vaguely tie in with Grays assertion that it was broken up in 1917. He also states that although it stood on chalk land it was formed from ironstone which occurs several miles away concluding that it was either moved here and then erected or that it was a glacial erratic. He goes on to say that it 'did not exceed 3 feet in height and was a cheesewring of three superimposed pieces of stone' that was 'religiously removed during ploughing and then replaced in position before it finally fell to pieces'.
English Heritage have this listed as "Site of an undated standing stone." suggesting that it isn't there anymore. They have it's grid referance as TA 1214 0332, although if they've never found it I doubt that is too great.
Be interesting if anyone can find it, I might have a go myself if I run out of things in North East Lincolnshire.
In another version of the story, the man on the ass is Jesus (see link)
In his book 'Hidden Lincolnshire' ISBN 1-85306-299-5 Adrian Gray records the 'stone' as three stones and reports that they were broken up in 1917. He gives their position as TA123033
This chap tracked the stone down but doesn't give it's position. If you email him he says he'll give you directions though.
I've got to say the modern photo doesn't really look like if was part of the original Sack Stone judging from the 1890's picture unless it was the lowest section - which isn't too clear in the old pic.