The story of origin of Bel Fruit is associated with Goddess Lakshmi. The link.
While in skanda Purana it is said that the bilva tree appeared from maa parvati's sweat and she resides in it.
The Importance of Bilva Fruit in Worship of Shiva Symbolically, Shiva is like the bell fruit – hard outside but soft inside. A story mentioned in the Brihad Dharma Purana states that.:
Maa Lakshmi used to offer 1000 lotuses to Lord Shiva on every puja. Once, two lotuses went missing from those thousand ones. At the time of worship when Lakshmi became extremely worried then Lord Vishnu said that Lakshmi's two breasts are as pious and auspicious as lotus and that she can offer those to Shiva.Then she cut off her breasts and offered them to Shiva. Shiva was pleased by her devotion and blessed her that, from now onwards her breasts will be there on the Bilva tree as its fruits and will be called as shree phal.
Acc to Sri Bilva Shtakam, bel tree grew from the breast of Maa Lakshmi.
"Lakshmyaascha stana utpannam Mahaadeva sadaa priyam, Bilva vriksham prayachchhaami eka bilvam Shivaarpanam. Darshanam bilva vrikshasya sparshanam paapanaashanam, Aghorapaapasamhaaram eka bilvam shivarpanam." ~
"Born from the breasts of Goddess Lakshmi, the Bilva tree is ever dear to Mahadeva. So I ask this tree to offer a Bilva leaf to Lord Shiva. To have darshan of the Bilva tree, and to touch it, frees one from sin. The most terrible karma is destroyed when a Bilva leaf is offered to Lord Shiva. The pale green leaves are aromatic. There are sadhus who sustain themselves on Bilva leaves alone. Every part of the bilva tree is useful, the root, bark, leaf, flowers and fruit –all have great medicinal value.!"
Shree Sooktam, praises goddess Mahalakshmi as.
“aadityavarNE tapasOdhijaatO Vanaspatistava vrukshOtha bilvaha
Tasya phalani tapasaa nudantu maayaanta raayaashcha baahyaa alakshmeehi”
"Oh Lakshmi, who is as bright as the sun, that noble tree, Bilva was brought forth by your devout austerities (tapas). May the fruits of the tree drive away my misfortunes and poverty both internal and external."
In “mahALakshmi ashTotara shatanaama stotram” we find Goddess Lakshmi described as “bilva nilayaM” the one who dwells in the Bilva Tree. -”Bilva nilayAm varArOhAm yashasvinIm”.
Though it already has the answer which states that.:
"Lord Vishnu said that Lakshmi's two breasts are as pious and auspicious as lotus and that she can offer those to Shiva."
But I am still confuse.
So my question is why breast why not any other body parts like lord vishnu who gave his Lotus eye to lord shiva because she is also called as kamal nayani means the one with the lotus eyes.?
Is it because breasts are considered as a symbol of nourishment (philosophically) n as a Shiva lingam is considered as the nirguna form of parambramha which symbolises the whole universe (as the universe is a combination of purusha and prakriti only) and maa Lakshmi as the wife or shakti of lord vishnu (whose duty is to nourish or preserve the universe) is also a nourisher n it was her duty and also lord shankar consider her (in form of maa Sita) as a mother just like lord vishnu consider maa Tripura sundari (a form of maa parvati) as a mother.? Can it be the reason.?