One of the important motifs in this play that the audience is introduced to straight away at the beginning of Act II is Willy's constant desire to buy seeds and try and plant them to grow some vegetables. Throughout the play at various points, his desire to buy seeds and his attempts to grow vegetables in his back yard is used as a signifier of how he feels his life is. At the beginning of Act II, he feels full of hope due to Biff's plan to go to Bill Oliver and ask to go into business with him, and thus his plan to buy seeds reflects this optimism. Seeds generally in the play represent his hopes (or lack of them) for the future, and also his failure as a father and as a businessman. He recognises that he has nothing to leave his children--no lasting, enduring legacy--and his constant reference to seeds reflects this. However, at this point in the play, Willy's desire to buy seeds is part of his hope that things are turning a corner. Note what he says to Linda:
Gee, on the way home tonight I'd like to buy some seeds... You wait, kid, before it's all over we're gonna get a little place out in the country, and I'll raise some vegetables, a couple of chickens...
Seeds therefore are used as a kind of barometer about Willy's state of will, and here are used to represent hope in a better future, in comparison with their usage in other parts of the play, where they represent Willy's crushing realisation that he is a failure and he will leave no legacy to his children.