A neighbour of mine, on the American east coast had a fire hydrant replaced in front of the house, right at the curb, and the fill used settled leaving a hole. He filled it with compost. Alas he now has road cantaloupes and courgettes (a type of small squash also called zucchini).
So is that Kelayim? (Clearly unintended, since he did not expect the compost to actually grow something).
And is he required to do something about it?
Would he be allowed to eat the fruit (ignoring whether it would be 'wise' to eat street fruit)?