If you receive a gift of cash from another individual, you do not have to pay income tax on this money. If your mother is a US citizen, she may need to file a gift tax return.
If you receive 100K or more from foreign sources, you must file a reporting form---Form 3520 to let the IRS know of this transaction, but it is not taxable as a gift.
Yes, sure thing, here is a link to tax info about gifts on the IRS website, you will see the second paragraph states the info you need!!!