See SEC FORMS LIST (in addition, see SEC Filings: Forms You Need to Know (Investopedia))
EXHIBITS to SEC Filings
Material Contracts are "Every contract not made in the ordinary course of business which is material"
Except, these should always be filed:
Exhibit Numbering (examples):
Ex 1 = Underwriting Agreement
Ex 2 = Merger Agreement
Ex 3.1 = Articles of Incorporation
Ex 3.2 = Bylaws
Ex 4 = Indenture
Ex 5 = Opinion
Ex 10 = Material Contracts
Ex 21 = List of Subsidiaries
Ex 23 = Consent
Ex 99 = Press Release