Antonia
Count yourself lucky your mother in law is so keen on your offspring. I've had a rocky relationship with mine over the years, my chief gripe being that she appears not to be that interested in her grandchildren (two dds, 2 and 6)and does not actually enjoy buying toys for them because she cannot relate to children playing.
Things are better as they get older and I realise the problem is that she does not know how to play or imagine herself into a child's position.
I hate to say this last bit, but as your precious offspring grows older he or she will cast wooden toys aside and positively adore the plastic ones. Sorry, but there it is. In the end, however many wooden toys you supply, he or she will make his/her own mind up. I suggest letting the relationship between grandmother and grandchild blossom in its own way - you are lucky.