Answer:
Solid sulfur has several crystalline forms- "allotropes". One common form, th eone most often encountered is called rhombic sulfur and this contains S8 rings. This is the form found in "flowers of sulfur" or "roll sulfur". <br/>
Sulfur is unusual as it can form rings with from 6 to 20 sulfur atoms, and can also form long chains, a property that chemists call catenation. The bright yellow colour of commercal rhombic sulfur is apparently caused by traces of S7 (cyclo-heptasulfur).<br/>
There is a good article in the English wikipedia "allotropes of sulfur" with a comprehensive list of the solid and gas forms as well as what occurs in liquid sulfur.