Babies and toddlers love to throw things, nibble and drool on them. When they’re toddlers, they will also start being able to stack them (not always neatly of course). Toddlers will explore their senses, and will learn about texture, how things work in the real world and the basics of geometry from a practical perspective. As in: this triangle doesn’t fit in that square.
Throwing things around trains their muscles, as well as their coordination. They’ll need both to get around in the world. Building blocks for toddlers won’t generally teach them anything about construction yet (though there are always exceptions), but being fun and manageable they will learn all kinds of things while playing with them. There are, from the toddler’s perspective, basically two kinds: the kind you can throw and the kind you can hide behind. Both are excellent playtime material. Building Blocks are a nice tool to awaken creativity and color and shape recognition in the Toddlers. Their young brains are encouraged to create new combinations, and they sure do love the encouragement, when they make something new. 
Non-Toxic 80 Piece Non-Recycled Quality foam Wonder Blocks: Soft, Quality, Waterproof, Safe & Quiet
These are the right size for your toddler to play with while sitting in their seat at the table. They’ll work for babies too: great to grab and drool on.
Your toddler will like the colors and shapes and you can start teaching them the words for both.
Smart Monkey Toys for babies, toddlers and older kids as well. How well I remember how four kids and one unconventional male baby sitter had fun with a large long cushion. Ages? 7 through 14. We named it, we fought for it… These building blocks are big enough for similar fun, though of course your children (boys and girls) might use them more conventionally: to build and play house for instance.
Big Soft Plush and Foam Building Blocks for Babies and Toddlers
Build them up and knock them down. These soft blocks are perfect for hands-on exploration of the geometric world. Assorted block shapes in primary colors enhance your child’s coordination, gross motor skills, and shape recognition.
Recommended for all ages so unleash the architect in your child.
We had loads of blocks in our house
My mom is a trained child psychologist. She had two big boxes in our house: one full of lego blocks, the other full of wooden blocks. It was great: the blocks didn’t all fit, but that didn’t matter, we made them into all kinds of buildings anyhow. With one grand child coming up, I do wonder if she still has them all lying around.
As kids we also loved climbing trees. We had three trees in our back yard. I had on favorite branch, not too far above the ground and my brother climbed all the way up. The other day he shared that he was always trying to figure out if he could climb that third tree. And the conclusion was always that – no, it could not be done. My brother was a very thoughtful kid, so there was no chance of him falling. Just of him sitting there high up in the tree and thinking about climbing further. Thankfully.
My boys played a lot with blocks. They owned a set of ordinary, plain wooden blocks and used them extensively and they played with a friend’s set of those rainbow blocks. There was something special about the size of them. Having “big” blocks means you could build walls, rooms, etc. that you could go into.