So, the other thread about giving away/lending baby stuff has made me wonder about a similar situation.
I had saved a box of my most favourite/precious toys and chucked all the others away/given them to charity when I moved out of home, with the express intention of keeping them for my future children.
DM instead 'gives' them all to my DN as much older DS had sprogs first, when she is still too little to look after them properly and keeps breaking stuff etc.
Mum's position is "I originally paid for it therefore it's not yours" < In fact she did this with lots of things, even books or DVDs I'd been given as Christmas presents she told me I had to leave at hers! I also used to regularly get "This is your present but it's for everyone to use really." 
I suppose you could say if I left them there (in storage in the shed) it's my own fault, but she's also asked me to bring back books etc I took with me that are now also getting ruined.
She also threw away the one stuffed toy I absolutely loved from age 4 up, and now tries to deny it/blame it on DF. and refuses to let me have the Piano I got for Birthday+/christmas when I was 10 (sounds extravagant but it was £100 from an old man nearby) because it'll make her dining room look bare.
I've always just thought, ok, I didn't buy it, so I guess it's hers.
AIBU to get annoyed by this though?