If I were to choose my oldest UFO, it would be sort of mine by default. I inherited some old hand pieced blocks from my husbands grandmother, who was hanging on to them from her mother. I'm the only one on this side of the family who quilts, so I was lucky and got those along with a crazy quilt that needs to have the edges finished, and an absolutly gorgous hand pieced hand quilted full size one that is still in excellent shape. The nearest we can figure for age of that one is well over 100 years. I've gotten these blocks out several times, and I just need to have something hit me as to how to finish them. There are several different "sets". Among them is a set of 3 very old polished cotton basket blocks that I have thought about framing instead of sewing. Most of the others are bow tie blocks or 4 patches.
I'm really not sure how many UFO's I actually have. Some people count them only if they have started cutting. But I have so many ideas, and fabrics pulled to go with them, that I feel like they are "started" even though I haven't actually done any cutting or sewing.
My biggest problem with finishing these is that I always seem to need to start something else for a gift or an occasion or something. I had planned to really get moving on some things this winter, but I was interrupted by a wedding, and now there are 2 babies coming this year that I want to do something for......