I found a pair in my backyard
Last summer I stepped out on the back porch for some air and while gazing around the yard I noticed a blue object toward the back fence. I wandered out to pick it up thinking it was some trash that had blown into my yard and when I bent over to pick it up I discovered it was a pair of satiny bikini type panties. They were fairly small leading me to think they were from a teenage girl. As I walked back toward the house to put them in the trash I noticed a fairly large amout of white stain in the crotch. I pretended to throw them in the trash (in case anyone was watching) and slipped them into my pocket.
When I got back inside I examined them more closely and it didn't look like just pussy juice in the crotch. It looked like there might also be some male cum stains. My mind raced and I wondered if some young girl had lost her virginity and then put her panties back on with cum oozing out of her pussy. Feeling the squishiness I believe she took a shortcut through my back yard and abandoned the wet panties while passing through.
I washed the panties but all the stains didn't come out. Since then I have used them several times to jackoff and usually add my cum to the stains in the crotch. Imagination is great for one's libido! Thanks to the teen girl that left her panties for a horny old man to find.