I just tried it with the summer seeds. Depending on the quality of the forage you use, they cost 215-322 to make 10, and they sell for 55 each, so it is worth crafting them into seeds to sell. Not sure about the other seasons. I'll have to try it.
I've got tons of money suddenly. At the start of summer I bought 36 of each type of seed and planted them all. I've had to abandon all my other pursuits (mining, social life, etc.) to keep up with the constant harvesting, and making new seeds to replant (plus watering the ones which don't have sprinklers yet) but I'm raking in lots of cash. My house is in the process of getting the second upgrade, then I'm going to build a new barn and coop and demolish the two I placed badly. I've spent a little time exploring the skull mine, too, but I feel like I don't have good enough equipment to do well in there yet. Need to find irridium, I suppose, though I don't know where's a good place to do that. Probably in the skull mine itself I guess...
EDIT: I wanted to take a screen shot of my whole farm but apparently doing so is a ridiculously complex process that involves modifying my hardware settings in BIOS. Jesus. Anyone know of another way of doing it, short of simply taking multiple shots and stitching them together manually? That actually sounds less complicated than using GeDoSaTo...