Par value in most states, including Delaware, is a relic of their corporate statutes that typically comes into play in calculating franchise taxes—it is the minimum issue price for a share of stock.
A typical par value is $0.00001. There is very little meaning to par value; nevertheless, because it does still have an impact on the annual franchise tax amount for Delaware corporations, you want to choose a very small number. Although California (and some other states) does not have the concept of par value, it is acceptable to state a par value for a California corporation, and it is generally a good idea to do so, because it may get used by other states in which the company does business in the future to set the minimum franchise taxes for those states.