What the monkey said

In the previous post, we translated the title and first sentence of a kids' story about a monkey and a crab. Now, here's what the monkey has to say:
「かきの　たねと　おむすびを　こうかんしようよ。　たねを　うえたら　おいしい　みが　どっさり　なるよ。」
The first word, かき, has a number of meanings. It connects with the next word, たね,using の. By looking for a good combination and looking at the illustration, you will discover that we are talking about the seed (たね) of a kaki (かき), a fruit that looks a bit like a tomato. The combination 'kaki seed' (かきの　たね) is connected with the next word, おむすび, which we know is 'rice ball' from the previous post, using と, meaning 'and'. So 'kaki seed and rice ball', which as a whole is followed by を, indicating that this is the direct object of the verb, which ends the sentence.
This verb is こうかんしようよ and has a few parts:

• the よ at the end indicates emphasis (more or less an exclamation mark)
• the こうかん at the beginning has various meanings, but in this context, the meaning 'exchange, substitution' makes sense, and it's also the top ranked definition if the 'Common Words only' check box is checked in the dictionary.
• The remaining middle part, しよう, is not so easy to find. Some Googling reveals that it's the volitional form of する, to do. The volitional typically translate to "let's [verb]".

So the whole sentence runs:
kaki['s] seed[and] rice ball[obj] exchange-do[vol][!]
or, freely translated:
Let's exchange the kaki seed and the rice ball!
or
Let's exchange your rice ball for my kaki seed!
Next post: what the monkey says next.