Hi Sue, here's some advice for various lawn ornament anchoring. Hope one or two help you with anchoring your ball ornaments in your lawn.

https://homeguides.sfgate.com/way-fasten-lawn-decorations-dont-blow-away-74555.html

I found this old thread on Hometalk where someone asked the same question and there are some wonderful answers: https://www.hometalk.com/3387994/q-how-do-you-secure-a-gazing-ball-so-the-wind-cant-blow-it-over

https://www.hunker.com/12398429/how-to-hold-down-and-secure-lawn-decorations

https://www.christmasnightinc.com/useful-information/how-properly-anchor-outdoor-christmas-decorations/

https://www.youtube.com/watch?v=R9A3jnaF0iQ

https://www.youtube.com/watch?v=1C1rjj_D1Lk

Hello,

If you are making them yourself, add into the top to the centre a rebar so you can spike it into the lawn. Hope that helps in some way. Happy Christmas!

If there's an opening, pour some small stones or sand inside.

How about spikes for a tent you could buy them at a camping store

Yes, wire them to camping stakes.