a tuckbox - filled with stuff ( not just tuck !)
I got both my dds tuck boxes - they are fabulous now really cool, I do remember seeing a camouflage print one whichmight appeal to boys.
Photos and posters to put up...and pins or blue tack to put them up with . I wondered why my dd2 didnt put up all the carefully chosen and printed pictures for weeks and weeks, until she remembered she had not blue tack at school.
Label absolutely everything....and talk to your son ...a lot...about how to manage lost kit etc, my dd2 gets really upset and stressed if she has lost something and thinks she will get into trouble ( not with me...i am just there to provide endless new kit) with teachers, and has been known to txt me at 8 oclock at night telling me i need to get her a new xyz by the next day , which isnt easy if you work fulltime and live an hour away.
A calender to pin up , with dates of leave out ( exeat) marked on them and ask him to choose something special to do on those weekends.
My girls always pick a favourite dinner to to have for last night at home and the first night home , we plan these in the holidays and write them on the house calender so they are not forgotten.
I also did the home duvet and pillows and new bed linen just for school.
But most of all talk about it all....discuss how it might feel ...and highlight the good stuff but do not brush over the bad, make sure your son knows its ok to feel sad sometimes .
My dds ( aged 10 and 15) both adore boarding, as I did !
good luck to your son.