They call these '相思豆' (Xiāng sī Dòu) in mandarin, which directly translates to 'lovesick bean' from the poem '红豆生南国，春来发几枝，愿君多采撷，此物最相思', to be used in the context where a boy and a girl are in love. Hence, these red saga seeds have been coined in English as 'love seeds'.
I guess part of the reason why it is called ' Xiāng sī dòu ' in mandarin, apart from being poetic since this is really a seed from the Saga Tree, is to distinguish this seed from the red bean (totally different plants) as the word '豆' (Dòu)= bean (more of a bean which is also the reproductive seed of a bean plant), and '种子' (Zhǒng zǐ) = seed, more of a mouthful(two syllable) to sound poetic.
Also, perhaps both beans and the saga seeds are encased in pods, so it was okay to use 'bean' instead of 'seed' in naming the saga seed in mandarin.
Finding this tree in the Neighbourhood has put a smile on my face whilst picking.
This has brought me back to when I was seven. Then, locating these saga seeds after a downpour would be one of my favourite pastimes apart from Cycling and locating animals in the hood). I only collected them, but I knew of some elderly relatives who would use them in pillows for newborns- well they used anything from rice(expensive), beans(cheaper) to saga seeds(free!)
Anyway, if you happen to be in Singapore, here's a map of saga trees in Singapore created by a nice guy