Thank you for submitting your item for appraisal. This appears to be a slice of an african elefant ivory tusk and a carved relief of an african woman attached to it, an expensive typical travel souvenir of the 1950s to 1970s. Such ivory plaques sold for 100-150 USD prior the ivory trade ban. Today you would need a CITES and proof that it was purchased pre 1976. The new rules ban the trade of ivory alltogether in some of the States in the USA. Either way, even if you can proof the import and ownership prior to 1976 and have paid for the documents you will find it difficult to sell, your State´s legal regulations apply.
There is no measurement for the sentimental value you might attach to it.