In May last year I posted about one of my obscure hobbies, spiking the local playground (above) with five and ten cent coins when I am out for a walk. Just one or two. The rationale is that the happiness displayed by a small child finding one of the coins is probably the best return you can get for the money nowadays.
I have never actually seen a kid find the coins.
But the other day I was out for my walk and saw that, in the playground, there were two kids and a man. The kids were climbing on the play equipment.
Their father was on his hands and knees, raking the woodchips with his fingers.
I guess you get your happiness wherever you can.