If you received funds from a 529 plan (also referred to as a "Coverdell ESA), you should have received a Form 1099-Q with your name and SSN listed as the Recipient.
(If you did not receive your own 1099-Q for these funds, then your grandparents would have gotten one and have to report it on their tax return).
If you did get a 1099-Q, enter it in the "Coverdell ESA and 529 Qualified Tuition Plan (1099-Q" interview in Federal Tax > Wages and Income > Less Common Income > Miscellaneous Income.
(For TurboTax online products, enter "1099q" in the Search Box and Select "Jump to 1099q")
