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An accountant would be a good thing, as you'd need to document what you sold, to whom, when, etc... and be able to account for the proceeds that you receive. Assuming that this is not a short sale situation (in which you would need bank approval and can't do a "lease back") you can certainly do so. It would need to be an "arms length transaction" on both sides (sale and lease) for it not to raise any red flags. That is, you need to sell it for fair market value, and you need to lease it for fair rental value. If you sell it for anything less, the difference between fair market value and the sales price will be a gift. And if you rent it for anything less, the difference will be a gift from your son to you, and would need to be accounted for.
It would be good to go through a realtor to do this, as he/she could run the numbers, set up the sale and lease, transfer, etc... An attorney wouldn't be required.
Hope that clears things up a bit. If you have any other questions, please let me know. If not, and you have not yet, please rate my answer AND press the "submit" button, if applicable. Please note that I don't get any credit for the time and effort that I spent on this answer unless and until you rate it positively (3 or more stars). Thank you, ***** ***** luck to you!