The only absolute certainty about this surname is that it is English and locational. It appears to derive from a 'lost' medieval site called 'Mus-law' or some similar sounding name which is either 'the hill (hlaw) of the mushrooms' or possible 'the hill of the mice'. However no such place has been identified in the English Medieval Village list of the Royal Historical Society, although 'Mushroom Castle' in Berkshire is a faint possibility. In fact there are several name spellings of some rarity which seem to owe their origins to this 'lost' place. These include Masho, Mishow, Mushawe, Mishaw, Mushrow, Mushawe, and possibly others. All are extremely rare as surnames. The extinction of medieval villages was quite a common practice. At least five thousand have disappeared without trace in the British Isles, only the surname now remaining to give any clue to the former existence. As to why they disappeared is usually unclear, but it may have been civil war, or plague, or more often a change in farming practice from arable to sheep farming in particular, with its need for fewer workers. In this case the recording examples are taken from widely different sources, and in widely different spellings. These recordings include Samuel Musho, the son of Samuel, christened at St Andrews church, Holborn, London, on February 15th 1730, and Thomas Mushrow, the son of Thomas and Elizabeth, christened at St Peters church, Liverpool, Lancashire, on February 1st 1874. The first recorded spelling of the family name is shown to be that of Mary Muishaw, which was dated January 13th 1730, married Thomas Horton at Wolverhampton, during the reign of King George 11, known as 'the last soldier king', 1727 - 1760. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.