Egg donation is not earned income. It should be reported on a 1099-MISC in box 3, not box 7, and even if it is reported in box 7, should be reported as "Other income." You are not engaged in an "ongoing trade or business" and the income is not subject to 15% self-employment tax.
Consequently, it also does not qualify as earned income to allow you to contribute to a traditional or Roth IRA.
For 2018, the standard deduction for a single person is $12,000. If your compensation is less than that, you will owe no income tax, and don't need to file a tax return at all. However, if you receive a 1099-MISC and don't file, you may receive a letter from the IRS asking why you did not file. So your options would be, file a tax return showing no tax owed but listing the 1099-MISC for the sake of listing it; or not filing, and responding to any IRS letter you may receive by telling them this was your only income and it was not from self-employment, so no tax is owed and no return was required.