there mite be a rose or perhaps one with his birth month or something fitting .

I can't track down any roses called 'Simon', I'm afraid. There are plants with 'simonii' after their first name, but nothing called 'Simon' on its own. Why not go for a rose like 'Golden Memories' or 'Thinking of You' ?

I found Geranium nodosum 'Simon' and Malus 'Simon' of the Rosaceae Family, on the RHS site, but was unable to find out more

The Geranium nodosum 'Simon' is a lovely pink flower.

There's also a deep pink Dahlia 'Simon', a Pelargonium 'Simon', Malus 'Simon' and a Lupin called Simon.

If you Google Simonii or Simonsii (Latin for Simon), you should find them easier. For example, there's a cherry tree called Simon (Prunus 'Simonii').

The plastic plaques are very nice for this purpose. Can
be moved around the garden if required. Wont get
overgrown. Cost about £20 depending how many words
you have on it.

Thank you all for your replies. I was looking for something for my aunt as she loves her garden and really wanted something personal. I have looked up the names you gave but I'm struggling to find anywhere to buy them from. Really appreciate the responses x