I received stock as payment for consulting services. How do I report the proceeds of the stock sale on my Schedule C?

You would include the fair market value of the stock when you received it in your line 1 "revenue" on Schedule C.  You would report the sale of the stock using the "Stocks, Mutual Funds, Bonds, Other" interview, recognizing a gain or loss between the proceeds and the fair market value of the stock at receipt.

Tom Young