Thanks for some good ideas. We do best when there are things DS is particularly interested in as he will ask questions till the cows come home. He is more than happy to initate conversation - but I can tell when he's bored as he falls back on asking me, "What are you doing?" every 2 seconds.
Go to the library and get some books out and discuss what's in them? Animals? How the weather works? My DS loves basic science sort of stuff, volcanos, the heart pumping blood, how you would get to the moon, that sort of thing?
Have you tried flipping it around and letting your DS guide the conversation? Most children that age find all sorts of fascinating things to talk about, things that, as adults we just don't notice. You will probably find yourself having fascinating conversations about various bugs, clouds, tree's, or pretty much anything. It is one of my favourite things about having children!
I'm bored with my topics of conversation with 2.10 y.o. DS. I think he is too -when he's bored he starts asking repetitive questions which drive me nuts. He is very verbal with good language skills and is interested in pretty much anything I instigate discussions about.
It isn't much better even when DH is around. We went on a walk yesterday afternoon and it was boring because we didn't have a lot to say.
I'm a SAHM and he doesn't go to nursery/pre-school. We also have 5 week old DS2. Things we talk a lot about are: plans for the week, train routes, maps, place names, numbers, letters, the bible, our upcoming house move.
Our lives aren't very exciting, especially since I find it hard getting out early before about 11am with 2 DC. We go to a couple of toddler groups, see friends and go swimming, but they don't really spark conversation.
Any ideas of how we can find more interesting things to talk about?