You will need the LLC written document/agreement. Hopefully, this has been set up by an attorney as a legal entity.
The parents will probably need to file a gift tax return for a gift of this value given to an LLC.
The value of a gift is generally the basis of the giver, not fmv of the property at the time of the gift. The basis allocation of the gifts given to the LLC will provide the value of the land vs the improvements.
The value of a property from a decedent is the fmv on the date of death, but you did not say the parents are deceased.
Per IRS Publication 551, Basis of Assets:
Property Received as a Gift
To figure the basis of property you receive as a gift, you must know its adjusted basis (defined earlier) to the donor just before it was given to you, its FMV at the time it was given to you, and any gift tax paid on it.
Then, it makes a difference if the giver's adjusted basis is greater than or lesser than FMV on the date of the gift.
For additional information, please refer to the following link:
IRS Publication 551, Basis of Assets
