If present, the balls would be very obvious by now -- by mid-summer in fact. Remember, males trees don't fruit.

What I did was collect balls in autumn & place over a plastic sheet out in the weather. Couple of frosts softened the balls, then I cut the smallest chunks I could & planted those in shallow rows.

Germination next spring was quite good, but because that spring I bought two Whiteshield OOs, I ignored the seedlings & let them die. Below's a nice female specimen in nearby Cumberland:

WEll, Beng, I am glad for your answer, but, around here, it will be likely close to October for the Osage orange "monkey balls' to show up. They are abundant here eventually in fall. So I will try to sow some once they are abundant, Beng. Unless our "minidrought' here in late summer has affected the Osage orange trees seed production, I should do fine. Poaky1

Poaky, the pic above was taken many yrs ago in mid-June (no fruit visible). I noticed the tree this yr and the developing fruit was easily visible (large, light-green "balls") among the branches from that distance in late August. Perhaps by "showing up", you mean they are lying on the ground....

Back in the day, when they were planted as fencerows... folks would sometimes gather them, place them in uncovered barrels and allow them to blet/rot into soupy(and, I'm sure, stinky) mess, then plow a furrow in the desired location and pour the slurry down the furrow. Seeds would sprout in a 'high stem-density' fashion, forming a nearly impenetrable barrier of 'living barbed wire' in just a few years.

I've left 'em lying in the bed of my pickup until well into the winter, when they're soft and mushy, then squashed them and picked out the seeds - but wear rubber gloves - the bletted fruit stinks, and the smell will stick with you for at least a couple of days, if you do it barehanded.

Thanks Lucky-p, and all the other replies. Poaky1