According to the tax law, yes, any persons making payments in excess of $600 to an individual is required to file a 1099-Misc and report these amounts paid individuals to the IRS! Thus, technically, your Mother would be required to provide you with a 1099-Misc and submit a 1096 to the IRS, thus reporting your income to the IRS.
But, I don't know why you claimed this amount on your taxes? Your Mother could have gifted you this amount and you would not have to pay any TAXES at all! According to the IRS tax code, "the Annual Gift Exclusions for 2007 and 2008 Tax Year is currently set at $12,000." This means the amount paid to you by your mother does not exceed $12,000 and may not be reportable income.
Now, if your Mother has already gifted you $12,000 then that is a different story. Your Mother may have to file a Gift tax return and report the payment to you.
I suggest that you immediately consult a CPA or a Tax Adviser and seek their advice as to whether or not you should consider amending your return and to determine whether the amount that you claimed on your tax return was appropriately considered as income or could it be considered a Gift. If it is determined to be a Gift, then perhaps you should amend your tax return and get a tax refund on the amount of taxes paid on the $6,000 received from your Mother.