to join with others in giving (help, money, ideas, suggestions etc)

donate, provide

to work or act together in order to bring about a result

aid, assist

to give (especially money) (to a charity etc)

make a gift of

paid for in advance

give money for goods, services

to (agree to) pay (a sum of money) regularly (to a cause, for something)

pay for use; contribute

a person who offers to do something (especially unpleasant or dangerous, or without being paid); to report (something) without being asked

offer to do something