Yes, your shed does need a base. This is to give it a solid, level foundation. Open soil will not help with the longevity of the shed itself or the contents within. The best materials to use to make your shed base are concrete, natural stone or wood.
Ilminster
Ilminster is a town and also civil parish in the countryside of south west Somerset, England, with a population of 5,808. Bypassed in 1988, the town now lies simply east of the junction of the A303 (London to Exeter) as well as the A358 (Taunton to Chard as well as Axminster). The church consists of the hamlet of Sea. Ilminster is stated in records dating from 725 and in a Charter approved to the Abbey of Muchelney (10 miles (16 kilometres) to the north) by King Ethelred in 995. Ilminster is also discussed in the Domesday Book (1086) as Ileminstre meaning 'The church on the River Isle' from the Old English ysle and also mynster. By this period Ilminster was a prospering community and also was provided the right to hold an once a week market, which it still does. Ilminster became part of the thousand of Abdick and Bulstone. In 1645 throughout the English Civil War Ilminster was the scene of an altercation in between legislative troops under Edward Massie as well as Royalist forces under Lord Goring who defended control of the bridges before the Battle of Langport. The community includes the structures of a sixteenth-century grade school, the Ilminster Meeting House, which works as the community's art gallery and opera house. There is also a Gospel Hall.