Tons of Lego. It made for excellent outdoor toys too. The sandbox was 80% sand and 20% Lego :">
Everything from crawlers over walkers to sailing devices. First powered by rubber bands (as was most catapult type Lego devices) to electrical powered ones ("overclocked", using the 12v electric train powersupply to drive the old 4.5v electric Lego engines).
Apart from that, a bit of "Action Man" and a *lot* of plastic kits from grand old names like Airfix and Matchbox. I think that at one time, I had the complete sortiment that those two companies offered. If not, then prety close
Add to that, the little chemist set, easy access to charcoal, nitrates, sulphur and other interesting stuff (and some long dead relative who left behind a bag of cordite) :D