If you have an appraisal that was done within 2 years of it being deeded to you, then you can use the amount on the appraisal as the FMV. If such an appraisal isn't available, then you can probably find it on the website of your county's property tax appraiser. Note that the latter will usually be significantly lower than an appraisal done by a private, licensed, certified property appraiser.
Usually, (but not always) an appraisal will be done when the property is sold or refinanced. So that last mortgage holder for that property should have an appraisal on file - even if the mortgage has been paid off.
