I don’t think many gardeners have tried planting companions for Coconut Trees-to-be. In the tropics, coconuts left on beaches, garden patches, anywhere… if undamaged will simply sprout, but not in areas with cool temperate zones.
It’s been over 8 months since I got these 2 green coconuts from a Mexican food store, took a gamble and put them in containers in hope of them sprouting. They did indeed sprout after 4 months.

Coconut seedling with a tomato plant & clover.

Coconut seedling with 2 tomato plants and a marigold.
They’ve been since re-potted in 5-gal buckets and fortunately this winter has been a mild one but I’m still prepared to move them indoors if the need arises.
Tomato seeds sowed in their pots are growing very well. I hope that with their vertical growth the coconut trunks might be good support/trellis for the tomatoes. To-date I have not found notes pairing tomatoes with coconuts so it would be interesting if these 2 plants are actually good companions.