I never knew that chipmunks were farmers until I lived here. Of course I have never lived where I had a porch with chipmunks living under it before. I put out birdseed for the birds. Most of it is sunflower seeds which seems to be what they prefer. So do the chipmunks. I found that several birds, cardinals, doves, bluejays, mockingbirds, do not like eating out of the hanging feeders and prefer to eat out of shallow pans on the ground or just off the ground. So do the chipmunks. And the squirrals.
But the chipmunks are the only ones that stuff their cheek pouches full of sunflower seeds then 'plant' the seeds somewhere. One of their favorite places to plant their seeds is in my pots of plants that I keep on the porch. Pots full of gerunims, begonias, impations, cactus, suculents, and other houseplants or small, pretty plants that I have grown this year.
Every few days a new 'crop' of sunflowers will appear in my pots around the plants that I put in them. So everytime I water I have to pull out the sunflower seedlings. If I don't the sunflowers will take over the pot. Sunflowers do not do well in pots. They just get too big.
Of course the chipmunks don't just plant in my pots. I will find a cluster of sunflower seedlings just about anywhere out in the grass. I don't mind that. The lawnmower will take care of them or if not they can just grow there.
I guess chipmunks are 'hard wired' to plant seeds. It is natures way of making sure that a plant will condinue to grow and produce seeds that the little critters and birds can eat and 'plant' to grow some more.
And in case your wondering, no, the squirrles don't do this. First they don't have check pouches to carry several seeds at a time. I have seen squirrels planting acorns out in the yard but never sunflowers. Acorns take longer to sprout and are available to eat in the winter time. I've never seen a chipmunk eating an acorn. I don't think they can crack them.