Hello, In modern grammar "There is" is used when the first noun after the verb "to be" is singular. Example There is a cat and flowers. There is a book, three beds, and a cat in the bedroom. Use "there are" when the first noun after the verb "to be" is plural. There are flowers and a cat. There are three beds,a book, and a cat in the bedroom. However, in older, traditional grammar books you might also find the following: There are a cat and flowers. There are a book, a cat, and a bed in the bedroom.

The most correct sentences is the first one: "There is a cat and flowers..."

As I remember, There is a cat and flowers - used in spoken infromal English, but not generally considered to be grammatically correct. There are a cat and flowers - grammatically correct(subject-verb agreement).

yes we said "there is a cat and flowers", we agree with the first word behind there is... but in poetry or literature there is some exception.