You can enter cash received as other self-employment income. Do not enter 1099 information unless you have a 1099. Enter cash this way:
Sign into your account and click Take me to my return
Click Federal on the left side-bar
Click Income & Expenses along the top of the screen
Scroll down to Self-Employment click Show more
Click Start or Revisit next to Income and Expenses
Click Edit next to the business name (or add the business)
On the next screen scroll down and click Add income for this work
On the next screen click the button for Additional income and other income. Includes 1099-K, cash,
checks, and other income.
(see screenshot)