I got married in 2007 in a strapless gown with a full skirt. Frustratingly the dry cleaner at the time wasn’t great so the very bottom of the edge of the skirt and the tulle under skirt is still dirty. One of the armpits is also slightly yellowed.
Therefore I don’t think the charity shops or the charities that make gowns into stillborn babies dresses would accept it? I wouldn’t want to just chuck it either as it’s 100% silk and was made here in the UK.