Originally Posted by
Brighty
It will depend on how big the pine cones are. Mowers have a front bumper ground clearance of around 50mm. If they're big enough and your lawn flat enough, they would probably just get pushed around. If smaller than 50mm, they will go under and get chopped, probably not good for the cutting blades or the motor. If they are a bit bigger than 50mm, they could get stuck under the front bumper, the mower will stop and give a lift error, then need manually restarting.
One option, depending on the size of your lawn, is not to have the mower set on a timer, just go out, do a pinecone sweep, then send the mower out manually., This is what i do as i have to do a sweep for dog eggs, dog and kids toys and make sure the wife hasn't left a duvet on the washing line that's touching the grass (yes that did happen once, messy). I have a fairly small garden and a massively over spec'd 430X, so i only need to send it out for an hour or 2 twice a week. If you're lawn is up near max capacity of your chosen mower, then it will need to be out mowing almost constantly, so the manual start will not be an option.
For the football goal, it will chew up the net (and duvets), so the options you have there are
1) If you're doing a manual start as described above, just move them out of the mower zone before you send it out
2) Pick a permanent site for the goals and lay your boundary wire around them, you can lay the wire into the goal itself so that will get cut, but you'd have long grass growing around the frame and back of the net, but you could move the goal and strim that every now and again?